# owb heat exchanger info? which one



## Madspeed (Sep 1, 2008)

Hey guys, newbie here looking for some info on owb. I'm looking at picking upa Heatmaster MF5000 from a semi local dealer. Plumbing into an already set in place heat exchanger in my hot air furnace. Which heat exchanger do you all use and recommend for the potable water? I see a couple of different types fom the small rectangular ones to a copper tube type.


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## iCreek (Sep 1, 2008)

Madspeed said:


> Which heat exchanger do you all use and recommend for the potable water? I see a couple of different types fom the small rectangular ones to a copper tube type.



I used an AIC Water to Water Plate, I think I found the guy on eBay. Here is a pic of it mounted up above my water to air exchanger.







Another pic prior to installation.


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## Madspeed (Sep 1, 2008)

Thats's an interesting install. i like the double hit by mounting inside the plenum like that. is that the typical install or your creation? You get that from the freeheat4u guy on ebay? How many plates is it and what size?

BTW, i got my heat exchanger already installed in the plenum, purchsed it from the freeheat4u gut. Nice piece!


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## Madspeed (Sep 1, 2008)

ok i see you changed the second pic, thanks!

is that copper or ss?


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## bassman (Sep 3, 2008)

are those all sharkbite fittings??

I have both a plate and home made sidearm and the sidearm is slow but works and the plate (30 plate) is very fast and will just about make instant hot water to the point where a storage tank/water heater is not needed!!

just make sure you have good rise .

I did a system that used a b&g pump so my water is making a return loop and instant at the tap .

I am a hobby plumber..... ha ha ha


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## oneoldbanjo (Sep 3, 2008)

Well I did overkill. I installed a sidearm unit and a plate. The hot water comes in from the boiler and goes into the plate first, then the sidearm, and then the heat exchanger in the furnace. The plate heater works so well we turn the valve off on the sidearm.....the plate makes our water so hot we don't want the sidearm making it any hotter. We actually turn the electric elements of our water heater off when the OWB is running and it acts like an insulated storage tank. The hot water goes into the water heater at about 160 degrees and will stay that way for a long time - normal use causes a flow of new hot water into the water heater and it stays hot.

Based on my experience......you only need a large plate exchanger.


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## LTREES (Sep 3, 2008)

Sorry for the ignorance  What is a side arm? Heard references to this prior, but me no understand.


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## oneoldbanjo (Sep 3, 2008)

A sidearm is a copper (tube in tube) heat exchanger. Mine has a 1" copper pipe inside a 2" copper pipe. The 1" pipe is connected to the drain opening from the water heater at the bottom and rises up and is connected to the opening for the Temperature and pressure relieve valve at the top of the water heater. The OWB is connected to the 2" line and the hot water flows into the top and the hot water flows down the pipe and exits at the bottom and is then run to the heat exchanger in the furnace and then back to the OWB. The hot water in the 2" pipe transfers heat to the water in the 1" pipe throught the pipe walls and as the water inside warms - it rises by convection (thermosiphon). Colder water flows out the of the water heater at the bottom to take place of the warm water that is rising......and a flow of water is created without pumps.

The plate exchanger provides instant hot water and heats the water as it enters the water heater - it does not keep it hot once the water has entered the water heater.

The sidearm heater warms the water more slowly and does not provide instant hot water - but it does provide a constant supply of heat to the water heater.


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## ms310 (Sep 3, 2008)

I am only using the side arm on mine. Yes i can run out of hot water but typically that is after two loads of laundry, and 4 showers. From what i am reading here i thing i would use the plate heater, for unlimited hot water. Basically like banjo and bassman with the side arm it heats the water and puts it into; in my case a 80gallon storage tank.


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## LTREES (Sep 3, 2008)




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## Madspeed (Sep 3, 2008)

Thanks for the info. Looks liek I'll be going with a 30 plater


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## Mister Twister (Sep 3, 2008)

There is another thing to consider using a plate exchanger also. Your water quality. They plug up real quickly if your water is hard or has a lot of minerals in it. I decided to go with a fin enhanced stainless steel sidearm from Alternative Heating & Supplies. http://alternativeheatingsupplies.com/. I have not completed my install yet so I don't have any feedback yet. Good luck with your install mine seems to be going well.


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## Madspeed (Sep 3, 2008)

well I can hoenestly say I dont know the mineral content of my water, but I live at the base of a mountain and there's no one or anything above me except for pure mountain spring water!! YUMMY!! I could probably bottle it and sell it its so refreshing!


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## iCreek (Sep 3, 2008)

Yup my (our) install, just something I thought about as we were doing it. My brother in law helped and bent the extra piece we put over the water to air exchanger and covered the square we cut in, also screwed so we can access later down the road if we need to. Still need to move my humidifier up a few inches.

My two exchangers were bought from the ct furnance guy, deepvoyage on eBay or Alternative Heating Supplies, same people from CT. My water to water plate is a 10 or 20 plate model. 






























Madspeed said:


> Thats's an interesting install. i like the double hit by mounting inside the plenum like that. is that the typical install or your creation? You get that from the freeheat4u guy on ebay? How many plates is it and what size?
> 
> BTW, i got my heat exchanger already installed in the plenum, purchased it from the freeheat4u gut. Nice piece!


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## iCreek (Sep 3, 2008)

oneoldbanjo said:


> The plate exchanger provides instant hot water and heats the water as it enters the water heater - it does not keep it hot once the water has entered the water heater.



Great point to mention....and I run my pump 'on demand' not 100% all the time. So if the house is not asking for heat, no water is flowing through my water to water heat exchanger... It works great for preheating the water that gets stored in the water heater tank, but if alot of time goes by I am sure it gets cooled down some. I still have my propane 'pilot' lite and set on a low temp. Used it last winter and did not notice the pilot igniting and heating the water, but I am sure it does have to. 

My main reason to do this was to not have to run additional PEX lines from my OWB for heating my 'potable' water. The plate cost me less that the two additional runs, and I was already tight with a 4" conduit, with the two hot and one cold for filling I have going to the OWB. Might not be the best solution, but I thought if I could preheat the water that goes into the water heater, I might save some propane on heating my water.


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## iCreek (Sep 3, 2008)

bassman said:


> are those all sharkbite fittings??



Yes they are, kind of expensive, but easy to use, we really like them.


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## Butch(OH) (Sep 3, 2008)

oneoldbanjo said:


> A sidearm is a copper (tube in tube) heat exchanger. Mine has a 1" copper pipe inside a 2" copper pipe. The 1" pipe is connected to the drain opening from the water heater at the bottom and rises up and is connected to the opening for the Temperature and pressure relieve valve at the top of the water heater. The OWB is connected to the 2" line and the hot water flows into the top and the hot water flows down the pipe and exits at the bottom and is then run to the heat exchanger in the furnace and then back to the OWB. The hot water in the 2" pipe transfers heat to the water in the 1" pipe throught the pipe walls and as the water inside warms - it rises by convection (thermosiphon). Colder water flows out the of the water heater at the bottom to take place of the warm water that is rising......and a flow of water is created without pumps.
> 
> The plate exchanger provides instant hot water and heats the water as it enters the water heater - it does not keep it hot once the water has entered the water heater.
> 
> The sidearm heater warms the water more slowly and does not provide instant hot water - but it does provide a constant supply of heat to the water heater.




Thats exactly what mine is,or will be when I get the flat plate installed. I have a side arm and it works OK but doesnt have the capacity to keep up with 5 people and clothes. I am going to keep it and just bought a 20 plate to preheat in additon to the tube. I should have all the hot my wife needs and then some. 

I noticed in the pics here that the installer did not include any by passes, or am I missing them? I have them on both the furnace unit and the domestic water tube.With the cost of copper tube, fittings and valves they add CONSIDERABLY to the cost of installtion. Anybody have coment on leaving them out?


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## RodneyG (Sep 4, 2008)

I've got a question about hooking up the heat exchangers. Do they hook up in series or parallel? If they hook up in series wouldn't you want to go through the water to air 1st. and hit the water to water plate exchanger last? Since you don't need 175* water going to your hot water system? Don't mean to to still your post madspeed just needing some info. I'm new to the OWB's got one on back order. I would like to get everything plumbed in before it gets here.

THANKS,Rodney


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## oneoldbanjo (Sep 4, 2008)

My Woodmaster dealer hooked up system so the hot water form the boiler enters the plate exchanger on the water heater first, then the sidearm on the water heater was next, and the furnace heat exchanger last.....all in series. The system works fine that way - we have never had a problem with the water heater using up too much energy from the OWB water.


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## barnyardman (Sep 4, 2008)

Heatmor has a water coil that looks like this http://www.outbackheatinginc.com/products/equipment.htm


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## Butch(OH) (Sep 4, 2008)

RodneyG said:


> I've got a question about hooking up the heat exchangers. Do they hook up in series or parallel? If they hook up in series wouldn't you want to go through the water to air 1st. and hit the water to water plate exchanger last? Since you don't need 175* water going to your hot water system? Don't mean to to still your post madspeed just needing some info. I'm new to the OWB's got one on back order. I would like to get everything plumbed in before it gets here.
> 
> THANKS,Rodney



There are differing ways to run the loop(s) Central Boilers catalogs have real nice illustrations of the various ways to hook them up. If you have forced air heat and are going to place a heat exchanger in the plenum a series system is widely used, same with existing boiler and wood boiler assist. All Mfgs recommend that the domestic water unit be first in line, or closest to the boiler, don't know why but I assume recovery times and yes the water will eventually be VERY hot if you have a side arm and you need a blending valve. Some people run parallel runs with small booster pumps to heat domestic water quicker and control temps better and they may have it right as I have a side arm and am installing a plate heater as this time because the side arm doesn't keep up with demand. I will have lots of money in my water heating by the time I am done as copper fittings are out of sight! 

In floor heating is a different animal and requires a parallel system with many runs, small pumps called "zoning pumps" and valves. I am a long ways from an expert on that setup,,, come to think of it I am a long ways from an expert on anything, LOL.


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## iCreek (Sep 4, 2008)

RodneyG said:


> I've got a question about hooking up the heat exchangers. Do they hook up in series or parallel? If they hook up in series wouldn't you want to go through the water to air 1st. and hit the water to water plate exchanger last? Since you don't need 175* water going to your hot water system? Don't mean to to still your post madspeed just needing some info. I'm new to the OWB's got one on back order. I would like to get everything plumbed in before it gets here.
> 
> THANKS,Rodney




Rodney, first welcome to the AS forums... Mine are in series and that is exactly what I am doing before I fire everything up this year, go to my water to air exchanger in the furnance, then to the water to water plate. Although I don't have any problems, that is just what I think makes the most sense.


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## RodneyG (Sep 4, 2008)

Thanks for the welcome and the replies.

If you were to run the exchangers in parallel in the loop would you need a pump for each exchanger? Or would the the main pump from the owb push enough hot water to supply both the water to air and the water to water plate? I'd like to find the most efficient way to install the unit the first time no matter if it is series or parallel. I'm confused about which way to go.

iCreek i'm like you it seems that if in series it would go to the water to air exchanger first, but i'm way under knowledged about this subject.

Any help from anyone would be greatly appreciated.

Thanks again Rodney


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## JAL (Sep 4, 2008)

My heat exchanger is a shell and tube type and it is hooked up in parallel to my LPG boiler. I also have domestic hot water hooked up as a zone off of the inside boiler so i don't need a heat exchanger for it. The pump on the OWB pumps through the heat exchanger top to bottom and the pump on the inside boiler bottom to top.

View attachment 77522


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## oneoldbanjo (Sep 5, 2008)

With the furnace and water heater in parallel the restance to flow will be less than if they are in series - however the exchanger with the least resistance receives the most flow. If you want to hook them up parallel I would suggest you install a valve on each leg so you can adjust the flow - or be able to close a valve to bypass one leg . That way you would be able to balance the flow if you found out one side received too much or too little flow - and you could bypass the furnace if you just wanted to keep your hot water tank operating.

I don't know the reason that the manufacturers and installers hook them up in series - water heater first - but there must be some reason and I don't expect that it is random. I would imagine that the people you buy your OWB furnace from could offer some guidance.

My system is hooked up in series with the water heater plate exchanger first, the sidearm on the water heater second, and the furnace last. The air out of my registers is about 100 degrees and it is a nice steady heat - it does not come on real hot for a short period of time and then shut off - it provides a nice steady supply of warm air for extended periods. My furnace blower is set on the low setting and you can barely hear the blower when it is running - our house is well insulated and we don't ever have to run the blower any faster.


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## mtfallsmikey (Sep 5, 2008)

*Don't forget*

Install a good Y-strainer with a blowdown before the HX, boys!


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## mrk585 (Nov 11, 2009)

*30 plate*

could i use a 30 plate on the hot side of my water heater and shut my gas off ? would it keep up . Instant hot water heater


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## mtfallsmikey (Nov 11, 2009)

mrk585 said:


> could i use a 30 plate on the hot side of my water heater and shut my gas off ? would it keep up . Instant hot water heater



should work...remember to look at the specs, how many GPM flow it will take, and how many GPM of ??? deg. water @ ??? temp. rise. A baseline is 100 deg. temp rise, on the output temp vs. input temp.


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## mrk585 (Nov 11, 2009)

*will it work - i thing it should*

the w/w xchanger is coming from my boiler storage tank inside so its first in line the in series in the w/a xchange I am going to try ti use my boiler water at a cool 150 my domistic water is 60-65 i would say my flow rates are about 20gpm from the boiler and domastic would be what ever is bing used most fausets are about 2.5 -3.0 gpm usage


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## trialanderror (Nov 12, 2009)

the biggest that'll fit!!!!

better to have and not need it to then need it and not have it!!!

i went with a 250K btu HX, that replaces the job of the propane that's rated for 80k....

fan turns 3-4 times an hr for at the most 3 minutes...


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## 12vdzl (Nov 13, 2009)

mrk585 said:


> could i use a 30 plate on the hot side of my water heater and shut my gas off ? would it keep up . Instant hot water heater




It'll keep up just fine. The whole time i was installing my boiler, my hot water heater (LP) decided it did not like it's life anymore. I bought a new Electic water heater, and need to upgrade my service panel (not enough room, nor amperage). At this time the water heater is only being heated by the 30 plate exchanger, and will keep it that way until next summer. Come next summer i will put the boiler and 30 plate echanger through it's paces to see how good they are, when i wash my deck (approx. 16'x40') with hot water.


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## mtfallsmikey (Nov 13, 2009)

http://icpindexing.mqgroup.com/documents/086477/48411250104.pdf

A PDF of Heil water/air HX spec sheets..... ...FYI.


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