Ask Caleffi
Welcome to the Ask Caleffi podcast series, now featuring our powerhouse tech team! Join Cody, Ryan, Matt, and Dan as they dive into the tricky heating and plumbing challenges they tackle every day.
These field experts share real-world insights to help contractors navigate even the toughest jobs with ease. Count on the team to keep things lively, mixing professional wisdom with the entertaining, relatable stories you’ve come to love.
Ask Caleffi
#28 What are the INs and OUTs of heat exchangers? (with John Siegenthaler)
Use Left/Right to seek, Home/End to jump to start or end. Hold shift to jump forward or backward.
John 'Siggy' Seigenthaler guest stars on an episode dedicated to all things heat exchange. How do you know which type of heat exchanger is best for your application? How do you keep them clean and operating efficiently? What is a convection coefficient? Why is turbulence important? Siggy answers these questions and more for hydronic and domestic hot water system.
Want to hear YOUR QUESTION on Ask Caleffi? Take this quick 4 question survey for your chance to hear your question in a future episode.
0:01
[Music] welcome to ask caleffi the podcast that
0:07
dives into real life problems that plumbing and hvac technicians face in the field we're your hosts from the
0:13
kalefi tech support team i'm greg tubbs and i'm dan ferkus welcome we look
0:18
forward to sharing some stories from our tech calls and using our background and expertise to make your days a little
0:24
easier
0:30
hey there welcome back to another episode of ask caleffi how are we doing dan hi we're doing good welcome back
0:36
everybody so what have you been up to lately oh boy a lot of home projects lately yeah
0:42
well you gotta get that honey-do list taken yeah you know that you know it's uh it's getting to be that time of year
0:47
right time to get out and play around in the woods there you go yeah
0:53
so we got a guest today we do it's exciting so you don't have to listen to just us talk to ourselves no no you guys
1:00
will be happy you don't have to listen to our voices today well they will hey well a little bit a little bit right okay
1:06
so who we got today we got john siegenthaler yeah we're lucky and happy to have john
1:13
on today so a lot of you know john is very involved with coffee with caleffi yeah you'll hear him on there in fact
1:20
you just heard him on there recently yeah just a super talented guy
1:25
uh smart guy well welcome john well good morning guys yeah so you want to maybe just give give
1:31
them a little bit of your background oh my background uh let's see well my father was a carpenter
1:38
so i grew up around construction grew up around tools they'll enjoy them still do so you grew
1:44
up around the job sites like we all yeah yeah yeah we're doing carpentry work
1:49
actually quite a quite a bit of different types of work not in great detail but i learned a lot
1:56
that kind of came back to me when i needed it later on and then i uh i actually went to
2:02
school my background is actually aeronautical engineering i wanted to fly
2:08
jet fighters didn't have the eyesight quite good enough for that so i said well if you can't fly them
2:14
let's design them once it's cool for aeronautical engineering oh actually that has some parallels quite a
2:21
few parallels with hydronics fluid mechanics heat transfer so forth okay and uh i get out of college in uh
2:29
let's see 1978 and went to work for a solar thermal company upstate new york
2:37
that was building solar collectors so basically i knew very little about hydronic uh from a practical standpoint
2:44
and more of a theoretical approach to fluid mechanics and heat transfer but uh the
2:51
first uh two or three years on the job we learned a lot about hydronics and again this was circa 19 late 1970s
3:00
okay and solar market was was thriving that actually grew very rapidly
3:07
and it also fell apart almost as rapidly when the tax credits expired in the
3:13
1980s okay yeah i recall that from you know kind of late 70s early 80s home was
3:20
always had those old solar collections you always would run into those houses on jobs where you'd go in there
3:26
the old collectors are on the top of the house on the roof and an old style water heater that i had
3:31
some sort of contraption on the side and i just remember looking and going wow look at all that yeah usually at that
3:37
point it was all abandoned but yeah still still in place yeah i actually uh well we built a house
3:43
in 1980 it did a lot of the work ourselves and i actually put in a solar thermal system and it's still operating
3:49
actually it has some of the the uh star max collectors on it right now a greenback system that does
3:57
well does most of our domestic water especially in the summer but you know contributes to some space heating in the
4:03
house uh back when we built text tubing wasn't available so we use copper tubing right for radiant floor heating and
4:10
that's all still in place still operating okay but as we were saying the solar thermal
4:16
market kind of fell apart and that ended up i ended up being laid off from the
4:22
company as a result of that and actually ended up going to a community college to
4:27
do teaching mechanical technology and some of the engineering science courses there just spent 27 years at
4:35
mohawk valley community college teaching wow and during that time
4:42
got more into hydronic systems so of course radiant
4:47
panel heating was really starting to come back in i'd say the late 1980s and the 1990s
4:54
so new materials new at that time pex tubing and so forth uh mixing valves and
5:01
you know what we take for granted today in the radius market or the hydrox market that was all relatively new back
5:08
then at least in north america so i actually developed a course in
5:14
hydronic heating that i taught at the community college and enjoyed that a lot and it also gave
5:20
opportunity to go out and do other consulting work
5:26
as an engineering company we designed hundreds of heating systems around hydronics
5:32
pretty much any heat source that could work we've we've worked with it
5:38
and uh wrote a textbook the textbook really came out of uh the preparation for
5:44
teaching the course at the community college sure wow you've been uh have enjoyed very much working in the
5:50
industry i never really strategically planned to work in this industry but
5:56
i've met a lot of great people and done a lot of uh interesting projects over the years
6:01
got to think back we've actually been doing this now for about 42 years something like that
6:08
so i'm an old timer and i have the gray hair to show anything yeah funny it's interesting background
6:16
it's it's fun it's funny how life changes from wanting to you know be a fighter pilot to getting
6:22
into the hydronics industry and i'm sure i'm sure you certainly enjoy that yeah yeah that's quite a
6:29
spectrum of uh of a career but uh yeah i enjoyed it very much
6:35
i i it sounds like it i mean you you're very compassionate about it for us and we we ran did a lot of
6:42
service work and and install and i mean even doing that will give you plenty of gray hair if you're like dan you have no
6:49
hair left at all i pulled all mine out well you know getting out in the field i
6:54
mean we've done some work you know i i haven't actually hired myself out as a
7:00
heating contractor per se but we've done work where we've gone in and
7:05
diagnosed systems and actually turned wrenches to help correct those right system guys i would encourage anybody
7:11
that's getting into engineering today especially if they're looking at hvac as
7:17
a career to get at least a summer job working with a mechanical contractor
7:23
and and really see what's involved in putting hardware together you know you'll definitely see things
7:30
that will help you in the design process later on yeah i agree with that you know
7:35
100 yeah i mean being coming out of the industry and out of the field
7:40
um and at one point you know i did sales in system design you know i did a lot of
7:46
system design for hydronic and geothermal systems and i and i worked with engineers closely and i know the
7:52
engineers that i worked with that had some field background we were just able to talk at a whole
7:58
different level and communicate at a whole different level and it made designing the project um a lot easier
8:04
and actually you know made a lot of good friendships that way because you're able to communicate at a different level because you know i don't
8:12
have the engineering experience i have a lot of system design experience
8:17
but i'm not an engineer i'm more of an install and service tech and them having
8:23
that some of that background just made made it far easier for us to communicate
8:28
and make make the projects more successful yes yeah you know
8:34
working in the field and seeing what what happens sometimes good hopefully most of the time good but sometimes it
8:40
doesn't go the way you plan it's very humbling and
8:45
there are engineers that could use more humbling [Laughter]
8:52
yeah but um no so that i think that's great advice i think that's certainly great
8:57
advice well speaking of putting hands on
9:03
different parts of the system and the hardware we're going to actually swing into
9:08
talking about heat exchangers today with you john yeah you just did you just
9:13
did the coffee with caleffi on heat exchangers for us so we thought you know what would be good to kind of parlay off
9:20
of that and talk about you know talk about heat exchangers
9:26
yeah yeah it's good topic it's uh certainly a broad topic and hydronics 29 has also got a lot of
9:34
good material on heat exchangers hydraulic and plumbing applications yeah
9:40
yeah it certainly does i mean there's so many different types of heat exchangers out there and they all have you know
9:45
similar i mean similar use they're you know exchanging heat but different applications for them
9:54
yeah um you know in in the ironics uh and as well as the
10:00
uh the coffee with caleffi we we categorize heat exchangers basically three types there's a shell and tube
10:07
heat exchanger there's a shell and coil heat exchangers and then there's flat plate heat exchangers
10:14
right the the common one in industrial or large
10:20
hydraulic systems typically has been the shell and tube design these have been around for decades
10:26
and they basically came out of an air
10:32
they were being applied especially in industrial applications they were up in some cases several hundred degrees
10:38
fahrenheit temperatures uh you know not just water but they might have been working with cooling oil
10:46
in some kind of an industrial process and also operating at relatively high
10:51
pressure so yeah they're they're out there and they still are there are several companies
10:56
that have those available but they are large and they are pretty heavy and you know the fact that they're
11:03
large and heavy means there's a lot of material in them and of course that adds to their cost it adds to their size
11:10
so in the context of residential and like commercial hydraulic applications they
11:16
aren't used that much these days um yeah guys in in residential light
11:22
commercial hydronic applications um the tubing show or i'm sorry shell and
11:28
tube is a correct way to say that that hit exchanger design doesn't get a lot of use today and it's
11:35
primarily because of size and cost in comparison to other alternatives more i'll say
11:42
contemporary alternatives and the flat plate heat exchanger really
11:47
has become dominant in the hvac industry now
11:52
again within the temperatures and pressures that most hydraulic systems are working at
11:58
right heat exchanger can easily be applied yeah i think i think in in the past when
12:05
i used the shell in tube it was when we were using a boiler to heat a pool i think that was the exchange for a pool
12:12
or a spa where we used the shell and tube heat exchange yeah that might have been an application where the tubes that
12:18
were carrying the pool water they might have been a titanium or a titanium alloy
12:23
with stainless steel uh so they can withstand the chlorination of the pool right yeah i think that was the only
12:30
application where i've i've ever used that okay so the the flat plate heat exchangers
12:36
today again in smaller systems residential light commercial systems normally it's going to be a braze plate
12:43
design where stacked up stainless steel plates that have been basically
12:49
stamped to a pattern that creates good turbulence in the flow good heat
12:55
transfer characteristics and then these plates are stacked up and they're raised together both
13:02
internally as well around the perimeter and so you get a unit that is completely
13:08
sealed pressure tested and they're available anywhere from really small units down like three
13:14
inches by eight inches maybe an inch thick right up to a large
13:20
bracelet would be probably 10 inches wide 20 inches tall and it might have 50 or 60 plates
13:27
deep in the staff and a you know large one like that under the right conditions could easily do
13:34
multiple millions of bqs per hour transfer rates right yeah i think that
13:40
was more common to what we used in the field absolutely i saw
13:45
quite a few more of those yeah in the field than i did any other type yeah i think when we use them a lot and greg
13:52
and i both have more of a residential background i mean i know we used to use them a lot
13:57
for hydronic systems when we would add a garage and do the garage heating where so that allowed us to put anti-freeze in
14:03
the garage floor and run straight water in the home or if you get somebody that
14:08
really has a lot of money and wants to do snow melt yep correct see them quite often there
14:15
yep uh snow metals and garage floor heating two common applications um they
14:20
can be used for domestic water heating as well that's that's done quite a bit in europe
14:26
uh we don't see it quite as much at this point in north america but it's not because it doesn't work it's
14:33
simply because we've the hydronics industry in the smaller system niche of the market has
14:39
gravitated more towards indirect tank type water heaters with internal coils which again is another type of heat
14:46
exchanger but one of the really important distinctions between
14:51
internal versus external heat exchangers it has to do with the rate of heat
14:57
transfer it's called convection coefficient and basically what a convection coefficient is
15:04
it's an indication of how well the heat can leave a surface or if it's water that's heating a surface
15:12
how well heat will transfer from the water to the surface right and the higher the numbers for the convection
15:17
coefficient the better that is and when you have an internal heat exchanger i think about a
15:24
standard indirect tank for domestic water heating you're pumping boiler water through the inside of that coil the fact that you're
15:31
using a pump or circulator to move that water you have what's called forced convection you have water moving through
15:38
there at a condition that is pretty much assuring its turbulent flow
15:44
and that's really good from a heat transfer standpoint turbulent flow is very desirable
15:50
because it actually brings up the convection coefficient substantially
15:57
now on the other side of that coil imagine the exterior surface of that coil where the domestic water is in
16:03
contact with it there's no pump there's no there's nothing pushing that water across that surface right that's natural
16:11
convection and it's a much weaker phenomena compared to forced convection so
16:18
with an indirect tank or really any kind of an inter coiled
16:23
heat exchanger the limitation is very much dependent on that natural
16:28
convection on that tank side of the coil that can be the bottleneck and quite
16:34
honestly that is something that contractors installers you really want to be aware of that
16:40
because uh for example if a tank that was
16:45
a customary design it might have oh anywhere from six to eight coils field
16:51
gold you know turns on that internal coil uh when you look at the ratings on those
16:57
coils they often will rate it with the boiler water at either 180 or 200 degrees fahrenheit so they're
17:03
rating it under assumed conditions of a very high temperature heat source
17:08
and you can get pretty good rates of heat transfer when you have water at that temperature eating domestic water
17:14
that might especially in the bottom of the tank might only be at 80 you know 90 degrees so you have a really high
17:22
delta t between the water that's giving up the heat and water that's accepting the heat
17:27
but if you take a tank like that and just try to apply it with the heat pump
17:32
that's going to be a major problem oh it is now you only have water at maybe 120
17:38
degrees going through that coil and you have much lower delta t and much lower
17:43
rates of heat transfer and typically what's going to happen there is because the coil can't dump
17:51
the heat into the domestic water as fast as the heat pump is producing heat
17:56
the water in that circuit between the heat pump and the coil the temperature goes up quickly and
18:03
eventually there's a safety either a high pressure switch or in some cases some temperature but something's
18:09
going to shut that heat pump off before you damage the compressor
18:14
um some kind of an internal safety and and that's just gonna you know if it locks out the heat pump you're gonna
18:20
have to reset it and the same thing's just gonna repeat so it it's definitely something to be aware
18:26
of if you're out there thinking about putting in some heat pumps and this could be geothermal water to water heat
18:32
pumps it could be air to water heat pumps but you really want to be
18:37
cognizant of that limitation on heat transfer in a standard indirect that's
18:43
where actually going back to a brace plate heat exchanger now you have a pump on both sides you
18:49
have uh right pumping heat between the heat pump and heat exchanger uh what i call the
18:55
primary side but you have another problem between the tank and the secondary side of the heat
19:00
exchanger so you have much higher convection coefficient then on the order of easily 10 to 12 times high
19:08
rates of heat transfer with the same temperatures and that you know in my opinion that is
19:14
definitely a preferred approach because right now there aren't a lot of indirect tanks on
19:21
the market that have really large internal coils you'll find it in the european market
19:28
but the north american market just has not produced a lot of products that
19:34
really are ideal for use with uh an indirect tank product that's ideal for
19:39
use with a with a heat pump right yeah i know with the heat pump like you said you're working with a lot lower source
19:46
temperature so yeah your recovery is quicker but also talking about about heat exchangers and heat pumps
19:55
i did we did a lot with geothermal water water and now you know you have the air
20:00
to water coming out another heat exchanger used that i saw
20:05
quite a bit was that coax heat exchanger in those water to water units
20:11
yep that's common uh it's a common uh design uh it's actually a tube within a
20:16
tube then it's all coiled up so it fits into a small area but a coaxial
20:22
heat exchanger commonly used when when you're transferring heat between either water
20:27
or a water solution with antifreeze and a refrigerant right so like again in
20:33
those water water units you've got two heat exchangers in there um you know one doing the earth loop
20:39
basically transferring heat from the fluid and the earthwork to the refrigerant on the evaporator side of the
20:44
heating mode and then the other one is acting as your condenser something you do from the refrigerant into the water
20:51
that's going to go keep the building yep those i recall that it was always refrigerant to water heat transfer in
20:58
those yeah and oftentimes you find those coils uh they're all wrapped up with uh some
21:04
type of elastomeric foam insulation so when they're operating at sub dew point temperatures they're
21:11
not they're not covered with condensation right well you know it's interesting so you know cluffy doesn't make heat
21:17
exchangers no we don't we make a lot of you know plumbing and hydraulic components one question i get quite a
21:23
bit from guys calling in is you know can i use a hydraulic separator to control temperature
21:31
from one side of the system to the other and and i always expect you know it's not really a heat exchanger yeah even
21:37
though people look at it and go well it looks like it's a heat exchanger you know because it's round and it's got
21:42
four boards coming out but then you kind of gotta talk them off the ledge a little bit and go look it's
21:48
not exactly what it is but yeah no it really is an intended uh you know as
21:54
a temperature control device but that being said i'm thinking if you picture a hydraulic
21:59
separator and you've got a modulating boiler or maybe even multiple modulating boilers on on the
22:06
source side of that hydraulic separator and then you have loads on the other
22:12
side maybe zones or different types of loads
22:17
when you're controlling the firing rate of those boilers you always want to make sure that the
22:22
sensor uh that is giving feedback to that boiler is on the
22:28
outlet of that hydraulic separator not not on the pipe that comes from the
22:34
boilers into the hydraulic separator but on the outlet and i i would
22:39
ideally put it in a well put it you know several pipe diameters down
22:44
uh and the reason for that is when you have zoning going on or you have multiple loads whether it's zone
22:51
valves that are opening and closing or circulators that are turning on and off if the flow the flow rate going through
22:59
or coming into the load side of the hydraulic separator is going to vary and so is the temperature
23:05
you know for example maybe i just turn on a zone that hasn't been on for several hours i've got relatively cool
23:11
water coming back and as that hits the hydraulic separator and you know it's definitely cooler so
23:19
um you can actually regulate your boiler output by measuring
23:26
downstream of the hydraulic separator if you have you know modulating modulation
23:32
capability in the boilers or again if it's a multiple boiler system or for that matter
23:38
multiple heat pumps um basically same concepts that we use with multiple
23:43
boiler systems today would also apply to for example multiple water to water geo
23:49
heat pumps or multiple air to water heat pumps
23:54
and we're seeing both those types of heat pumps today coming now with inverter compressors so they
24:02
they have modulation capability down to oh roughly 30 to 40 percent of their
24:07
full output so uh yeah you you can
24:12
indirectly control the water temperature going to your load through a hydrologic separator but to
24:19
your point guys it really isn't designed specifically for that function
24:24
uh it can it can serve as i guess i i would
24:30
i would say you know we're using it primarily to separate the flow dynamics of the boiler
24:37
pump from the load pump or you know multiple pumps on each side of the separator
24:43
and it also can do a really good job with air separation and dirt separation and magnetic particle separation
24:50
that's a primary intent of that device but with that sensor on the output side
24:57
and with feedback to the boiler uh you know you can
25:02
achieve the temperature that you're trying to on the outlet of the separator in effect uh
25:08
you know by modulation modulating the the boiler system right well that's you know with the advantages we have today
25:15
with variable speed pumps and modulating you know modulating boilers
25:22
inverter compressors i mean you have a lot more control and flexibility than
25:27
you would have had years ago with the with you know the mid efficient single stage boilers and fixed speed pumps you
25:33
just you can get a system more refined you can do a lot
25:38
more with it yeah we we have been asked and i suspect you guys probably get this question too
25:44
you know can i use a high heat exchanger in place of a hydraulic separator oh yeah yeah we do get that yeah and and
25:52
yeah you know you can why think about it doesn't yeah the heat exchanger really isn't designed
25:58
for air separation or for dirt separation um so you're not getting those functions
26:04
you're gonna have to add that functionality with other components and unless there's some
26:11
reason you're trying to separate the fluids that are on the boiler side of the system from the load side of the
26:17
system you know where you want absolutely no contact between those fluids there's
26:23
really no reason to separate to use a heat exchanger there it probably would be
26:28
more expensive than a hydraulic separator and the other thing is anytime you put a heat exchanger in you
26:35
have to have a temperature difference to drive heat through it so what that would do
26:41
let's say we're trying to achieve i'm just picking a number here i'm trying to achieve 100 degree water on my load side
26:47
i'd probably need to have at least 100 510 depending on the sizing of the heat
26:53
exchanger i definitely need to have a higher water temperature on the source side of that heat exchanger and if
27:00
that's a heat pump or even if it's a modulating condensing boiler that's forcing the boiler to operate at or
27:07
whatever the heat source is it's forcing it to operate at a higher temperature and that takes the efficiency down
27:13
yeah exactly that's kind of where my thought went when you start looking at
27:18
elevating your source temperature to mix down for your load i mean that
27:25
it's inefficient or less efficient to do that it is with modern sources you know in
27:32
days past when we're running boilers at 160 180 200 degrees fahrenheit
27:38
you really didn't get much of a change in efficiency but today it really to squeeze the best
27:44
efficiency out of either a heat pump or a mod convoiter you want to keep that water temperature as low as possible and
27:51
you know this kind of comes back to sizing heat exchangers if you're if you are working with heat
27:57
exchangers in systems with these contemporary heat sources you want to have a pretty small what we
28:03
call approach temperature difference and and that's a pretty simple idea it's the difference between the incoming fluid
28:09
that is bringing the heat to the heat exchanger and the leaving fluid that is
28:15
carrying that heat to the load and i usually suggest nothing more than a 5
28:20
degree fahrenheit under full rate of heat transfer in other words you look at what your
28:26
maximum output is on your heat source and you want to push that through the
28:32
heat exchanger with no more than a 5 degree temperature difference between that incoming fluid from the heat source
28:38
and the leaving fluid going to the load so you know that minimizes that what we
28:43
call a thermal penalty associated with having a heat exchanger right you get more of a direct exchange
28:49
across that heat exchanger right you're you know the hypothetical perfect heat exchanger
28:56
would have a zero degree approach temperature difference so you could send 100 degree water in from from a heat
29:02
source and you could have 100 degree water going to the load well in theory that needs an infinite
29:08
surface area to do that so it's it you can't do it from a practical or a cost standpoint
29:14
but there are applications today with flat flight heat exchangers where they're actually running at about a two
29:19
degree fahrenheit approach temperature difference um and that's that's good from the
29:25
standpoint of heat source efficiency but the caveat is what's it costing you to do that
29:32
um right yeah you look at your heat exchanger sizing just to achieve that
29:39
there's a lot of cost there so if you're gonna if you're trying to go from a five degree approach temperature difference
29:45
to a two and it's adding a thousand dollars to the project it's probably not
29:50
going to have a reasonable return on investment to do that right right
29:57
yeah sizing's a a pretty important thing when it comes to anything you know i feel in in any project
30:04
you know it is and you know the good news about sizing today most of the companies that sell heat
30:11
exchangers pay off sizing software that's available to designers or
30:16
engineers most of most of it's free you know you can go online and either
30:21
download the software or you can use it directly online and you can basically put in what i call the
30:28
what if conditions you know what what if my source water is at 120 degrees and i want my load water
30:35
to be at 110 and you put in the flow rate and it will
30:41
size heat exchangers based on those inputs and it'll actually check things like you
30:47
know if you're trying to inadvertently say i'm trying to move 200 000 bq per
30:52
hour into the heat exchanger but i'm only taking 190 000 out well that's really that's impossible you have to
30:59
have a heat balance across the heat exchanger so it'll identify those conditions and
31:04
tell you basically you know you're over specifying the operating conditions you need to
31:12
you know either reduce the number of inputs you have or let the
31:18
software actually work out the solution for you and the nice thing about doing that there are some really intense
31:25
calculations if you look at it theoretically you could do this by hand with a calculator but it would take you hours
31:32
to go through the iterations that you can do in a few minutes with this online software so i use it quite a bit anytime
31:40
i'm sizing up the heat exchanger yeah well that's it it's an important tool because you're right
31:47
oversizing heat exchanger adds a lot of cost and obviously undersizing it is going to get you in trouble and greg and
31:53
i have come out of the service side so we don't like to be in trouble so
31:59
yeah that's certainly important but no this is great i mean it was nice to to get on and and talk about the
32:05
different types of heat exchangers and design and and sizing yeah yeah another another point too on
32:14
to get good and maintain good transfer i mean a heat exchanger is not really a
32:19
component that is going to wear out um you know like like a boiler
32:25
eventually a boiler succumbs you know on the combustion side or whatever but a heat exchanger that's properly
32:31
maintained can last for decades uh assuming you know you've got
32:37
most of these heat exchangers today uh the flat plates are 316 or 304 stainless
32:43
so you've got a very corrosion resistant material to begin with but keeping dirt and debris
32:50
out of those heat exchangers is especially important with flat plates because
32:55
they have pretty small narrow passages they basically pack a lot of heat transfer surface area into
33:03
a pretty small package compared to let's say a shell and two heat exchanger so
33:09
uh you don't want solder bulbs you don't want teflon tape you don't want whatever crud might be in you know in the system
33:16
because you haven't either properly flushed it out or you know you don't have a dirt separation function in the
33:23
system um it's important to uh always filter
33:28
upstream of i i like to install the dirt separation upstream of not only the heat exchanger
33:34
but also the circulator that pumps the flow through the heat exchanger and we
33:39
show some details on that in hydronics 29 sure between that and fluid quality you know
33:46
if you're you got hard water even if it's made of stainless
33:51
still going to have problems there yeah so water water quality and good dirt separation is important
33:58
for sure water quality in a closed loop system i know you know you've done conversations with
34:03
with mark on that and we've you know we've got i forgot which hydronics it is but we
34:08
deal with water quality quite a bit um and one of the things that that i
34:14
have asked um sometimes it's kind of a pushback against the use of brake plate
34:20
heat exchangers in domestic hot water somebody will say well if i have hard
34:26
water i'm going to scale up that heat exchanger and they're right absolute
34:32
but you're going to scale up any heat exchanging device if you have hard water
34:37
so if you think that using an indirect tank is somehow going to protect you against
34:43
that without dealing with the hardness of the water you're going to be very mistaken
34:50
what will happen with those indirect tanks if you have hard water
34:56
and again these these problems are actually made worse by high water temperatures coming into the coil so
35:02
let's say we just gonna say that i was just going to say that high source temperature high source
35:08
temperature so yeah yeah not too interesting yeah it
35:14
it's you're right at the source in in a tankless water heater yep so let's say yeah we're putting 200
35:20
degree water from the boiler through the coil on the other side of that coil we got domestic water with you know high
35:26
high total dissolved solids that's just going to plate out on the external surface of that coil so the performance of that
35:33
coil is going to go down steadily and the more it operates the
35:39
more scale you're going to build and eventually even though the coil isn't leaking you put so much
35:46
scaled up material on the wall domestic water side of that coil and you have no way to clean it that's that's the other
35:52
important factor there's no way you can go in there and effectively clean that coil so at that point that whole tank is
36:00
basically toast right uh with a brace plate you can set up
36:05
valving and it's very similar to the valving that's been used today to clean tankless water heaters it's basically
36:12
two dual function purging valves where you you would isolate the domestic water
36:17
side of the heat exchanger and then you would hook up some hoses and a thumb pump and probably a mild
36:23
acid solution i'm not sure if it's citric acid or what what the chemistry
36:29
of the acid is it's not a highly aggressive acid but basically you're circulating an acid
36:35
water solution through the domestic side of that bracelet heat exchanger and you're
36:41
you're reacting with the alkaline materials calcium scale magnesium scale
36:47
and you're hopefully going to remove most of that so you can do a pretty effective
36:53
cleaning of the brace plate heat exchanger if you install the valving that you need and there are
37:00
several companies that make kits basically it's a five gallon pail a little sump pump and some hoses
37:07
and uh and a solution that you would pump through the heat exchanger and then once you've cleaned it
37:13
uh basically just flush it out with water open those valves back up and your back back in operation so i actually
37:19
think a bracelet heat exchanger in a situation like that has the advantage that it can be cleaned
37:26
actually on both sides if necessary whereas an internal coil in a tank
37:32
you really can't clean the domestic water side of it yeah no there's no way you'd get in there to clean that
37:39
um but bottom line is i tell people look if you've got hard water you're going to scale anything so you know the argument
37:46
of i have hard water therefore i shouldn't use a bracelet heat exchanger for domestic water heating is kind of
37:53
right it's really you know it it isn't a good logical argument because ultimately you've got
38:00
to treat that water or you know any heat exchangers can eventually fail yeah because at that
38:05
point whether it's a storage uh conventional tank style storage tank uh indirect
38:12
uh tankless water heater if you've got hard water it's gonna affect any of those products it does
38:18
yeah boy i think we covered yeah heat exchangers really well yeah and some
38:26
yeah i think if you guys want to learn more remember uh john just did our coffee with cluffy on heat exchangers
38:31
that's available on our youtube channel and then we've got idronics29 coming out
38:36
on or out on heat exchangers yeah so go check that out john thanks for joining us we totally
38:43
appreciate it yeah i look forward to seeing you guys at some point
38:49
thank you for tuning in if you ever need help please feel free to contact our tech support team anytime at
38:56
techsupport.us calefi.com or call us during our
39:01
business hours at 7 30 a.m to 4 30 p.m central time
39:08
at 414-238-2360
39:18
[Music]