Water Heater vs. Boiler

michael_13

I'm building my first house out here on the Cape--not a plumber-- and will be running my own radiant tubing. the company I'm buying my tubing and aluminum from sells a Polaris hot water heater that they claim will do the work of a boiler with much greater efficiency for both the radiant and the domestic HW. I've never seen a system like this before but it makes sense--why have a boiler heating water more than it has to only to get mixed back down to 125 when you can have a unit that only heats it to where it has to be? Can someone out there weigh in on this?
Got another question, which I'll also post separately--I've heard one horror story where the aluminum fins which get stapled up around the pex tubing "pop" when the heat comes on and makes a racket--has this happened to anyone else? any way to use the fins but prevent that from happening?

thanks everyone!

michael_13

Pex a'poppin'

I'm about to install a radiant floor system using the aluminum fins that staple to the underside of the subfloor. A local plumber told me I should think twice, that on one job he was on whenever the heat came on, the pex, expanding in its aluminum pocket, would make popping sounds all over the floor--sort of defeating the idea of a "silent" heating system. anyone else ever heard of this happening? is there some way of preventing this?
I really can't use gypcrete on this job and don't know of another way to do radiant effectively.

thanks for helping!

Robert O'Connor_7

Michael..

Does the system you purchased use the water for both heating & domestic hot water? If so, I strongly suggest you rethink this idea. First off, what is the heat loss of the building? Was a heatloss calculation done? If so, by what method? Thats a start. Open/Combinded radiant systems are by nature dangerous and can lead to health concearns such as Leigonella disease. Is tubing that was supplied have a OXY barrier in it? I suggest you research this more by looking through the arhcives on this site and others before you put your health at risk..Robert O'Connor/NJ

ed wallace

radiant

mike before you get in over your head get in touch with a company that specilizes in radiant heat waterheaters for radiant systems are illegal in the state of ma. have a full heat loss done do research on radiant dont be a fool and have to live with a bad install

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Joe_51

Micheal, I was is the same EXACT situation as you are in right now last year. I went so far with the water heater idea that I actually had it in my basement. I ended up driving it back 2 hours to where I picked it up. No lie. I'm guessing your a DIY'er (like myself) looking to save a bunch of money by installing it yourself. Definatly can be done. I did it. First off you need a PEX pipe that has a Oxygen barier.Your wasting your time and money using anything else. You need someone to do a room by room heatloss calculation....then have someone else do it,....and then do it yourself.You need to come up with a zoning stratagy that will work for your home, lifestyle and is as energy efficient as possible. Energy prices are only going up !!! I'm not saying anything bad about the company you're considering....the company owner started a thread about bashing his systems and was slaughtered by professionals on the RPA site.( maybe the thread is still available on their site to view.) I'm no wet head by any stretch of the imagination and might not be worthy to carry the tools of some of the guys who post here but I do know this.....I wouldn't use a water heater for my heat source and definatly not combine it with my domestic water.Contact me if you want to talk about what hurdles you'll need to jump through from a DIY'ers point of view. Joey

Robert O'Connor_7

Open Direct Systems.....N/G!!!

Michael, might I suggest reading in the "Commentaries" Section of the RPA Web site. I think you'll be re-thinking this approach....Robert O'Connor/NJ

bill clinton_3

That Polaris

water heater can certainly do a wonderful and efficient job heating your house. Be aware of three issues:
1. Make sure the local inspector will sign off on a water heater used for space heating. Some won't, and they are usually within their rights to refuse.

2. NEVER mix the water that goes through the heating system with water you drink or shower with. The shower is the most dangerous as it's where you can breathe in contaminated droplets. This means the Polaris does ONLY space heating, or you install a heat exchanger to separate the two functions. (Inspectors should have no problem with a dual system that uses a heat exchanger).

3. Be ready to change ignitors frequently. I like the Polaris a lot and install it frequently, but ignitors ARE a problem.


Bill

Unknown

keep in mind

polaris units want to be run at 160, whether or not you need that water temperature, or you can corrode certain parts of their assembly.

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Unknown

what he said

do not do an open system.

However, I *believe* polaris has fixed their ignitor problem with the newer units. Might be wrong, haven't worked with many of the newer ones, but that was the impression I got.

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Unknown

you have to pay attention to the installation details and I would most strongly recommend a reset system with either a motorized mixing valve or variable speed injection to get around the potential noise problems. Also use a decent plate with a lot of staples.

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Unknown

this isn't entirely accurate; there is a cost ratio involved with trading o2 pipe for non ferrous pumps and sometimes it works out in favor of the pipe, depending on what brand you're using. more pipe and less pumps and it becomes more and more viable.

with a heat exchanger it can be a perfectly viable option. without one, walk away.

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Unknown

also

another option is heavy gauge plates. more expensive but they perform WAAAY better and there are almost no noise issues.

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DaveGateway

Other WH's

The Polaris is pricey also. Bradford WHite makes a combo WH with a PEX coil inside as a HX. Of course you'll be lucky if it lasts 10 yrs like any other WH. Triagle Tube has a nice SS tank (for domestic HW) inside a steel tank (for heat) combo, but not cheap. Maybe a wall hung combo boiler like the BAXI Luna might be a good middle ground since it's modulating.

bill clinton_3

fixed Polaris

Polaris has changed the ignitor. My thus far limited experience points toward the problem not being solved. The 160* recommendation is, according to my information, for the sake of the ignitor: Keeps condensate out of the combustion chamber.

Bill

Unknown

there are options

However very few with the efficiency of the Polaris.

we find that using an external HE with the BW units is cheaper than the combo unit.

The baxi is a great unit, as long as your DHW requirements are fairly modest. Can't put a lot of GPM through their domestic coils.

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Unknown

I see

good info to have; thanks bill!

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