I can’t handle all these desions. Do I use a quality efficient boiler or a Polaris type water heater for my heat source for my radiant heat install. I have heat loss of 100,000 btu but the 11,000 ft elevation almost doubles that. My pockets aren’t deep enough for a $7000 VIESSMAN
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Replies
prestige claims to have a 96% efficiency rating.
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I wondered what to do myself a couple years ago. I decided against the Polaris due to the size, and reading online some very negative comments on them around that time. I think that most of the comments were on the flame sensor failing often. I have since realized that this is not that major of an issue if you are able to change the part yourself, and keep a spare on hand.
I was looking for something around 100,000 btu. The Polaris would have worked out. I also was looking into Munchkin, NTI Trinity (New York Thermal), Weil Mclain Ultra, and similar units that I can't remember off hand. The main thing that I was looking for was a super high efficiency unit, all of which had a modulating pilotless burner in sealed combustion chamber. Due to the high efficiency they all direct vent.
I liked the idea of the NTI Trinity unit vs. the other tankless boilers due to it being wall hanging. It is very small. This ended up being what I was looking for, but I would have settled on any of the similar units if I got a great price on it. I got a new open box Trinity on e-bay for about $500 less than I could get it from a dealer. That sealed the deal. I paid $1900 I think. It was the more expensive one with the domestic hot water heat exchanger unit in it.
I am extremely happy with it. It has been run for 3 heating seasons now, and it also does our domestic hot water. Our summer gas bill is 1/3 what it was for our old tank unit (our only other gas appliance is our stove which sees little use in the summer. Our Winter bill is about $100 less per month than with our old steam heat boiler (went from about $300 to $200).
The unit is not perfect though. The flame sensor went out in it after the first year. This part was about $20 for a similar one that the local plumbing supply house had in stock. It was not identical, but it hasn't seemed to matter. It so far has lasted twice as long as the original one. Now that I know better, I would not have held this against the Polaris. This is a part that all of these type of units have, and the most likely part to fail.
FYI... I bought the unit when I switched from steam heat to radiant floor heat. I have an open loop heat system (flushed with fresh water everytime we use hot water), which my boiler says that it should not be used for. I have had no problems yet. It has a stainless steel heat exchanger in it, so there shouldn't be a corrosion issue. It seems that they are concerned that this could get air bubbles into the system, so I added some air capture/removal designs into the system.
Around the time that I made my purchase Munchkin came out with a wall hanging version of their unit which would have been my other first choice. I think that both NTI Trinity and Munchkin make a unit in the 200,000 BTU range for about $2500 to $3000. The Weil-Mclain Ultra was somewhere in the $4000 range and had an aluminum heat exchanger rather than stainless steel.
So to answer you question, it's hard for me to think that you will be sorry either way. The advantage to the Polaris is the tank if you are going to use it for your domestic hot water also, but then you need an open loop system. If you aren't going to use it that way, then the Polaris doesn't have any advantage that I can think of. If you have a closed loop system the NTI Trinity, Munchkin, and several others have a unit to meet your needs for a similar price, without storing all that unnecessary water.
A vote here for the Munchkin with the visions controller.
But with that said I would check what is available locally for you. If you need parts and service it is nice to have a unit the techs are familiar with. You don't want to pay them for some on the job training on new equipment.
Remember, Mod-Con boilers work best when properly sized (not oversized). Check out heatinghelp.com go to "the wall" do a search. Lots of good information there, lots of good guy's too. Some are a little hard headed at times but are good people.
Good Luck,
Garett
I am not a fan of open-loop systems due to the issues with bacterial growth in your home water system. So even if you were to consider a Polaris as a heat source, I'd use a HX to convert the home heating system to closed-loop, even if that's not the way that a Polaris is supposed to be installed.Next, a modulating/condensing boiler is the best choice for a radiant heating system. It achieves great efficiency and will pay for itself in a matter of years. You can go with the cheapie stuff like tankless water heaters, but if the home is a year-round occupied structure, going to high efficiency makes the most sense in my book.What brand to chose is yet another matter. If you're living in a remote area in a off-grid home, then a $$$ Vitodens may very well be justifiable compared to a less expensive Ultra or Trinity, because it allegedly consumes 8x less electrical power than a Ultra, for example (according to EERE). The reduction in genset runtime or solar panels could make a big difference in the total.The thing to look for is an appliance that is well-supported locally. The supply houses ought to stock the parts, the installers ought to have experience installing the thing, the maintenance folk ought to have an idea of how to maintain it. I happen to like the Vitodens best, but I live within 1hrs drive of the US headquarters, lots of them are installed around here, and I have a couple of guys in the trade that I know I can call if I wanted one. In the meantime, I continue my contrarian ambitions with the oil-fired Vitola in the basement.
Edited 3/24/2006 10:54 am ET by Constantin
Thank you guys for the input!!! I would agree with the fact that the local support is important but this home is in BFE and the closest trustworthy support is 2 hrs away, so this must be a self-installed and self-maintained system. I will continue my research based on your advise. thanks again!!!
If you can afford a polaris, you can afford a modulating/condensing boiler. Perhaps not a viessmann, which is top of the line ;) but there are many others, and with your load you would be crazy to use anything else, especially if this is an all-radiant or all-low-temp system.
The first question you need to answer is what mod/con boilers are used in your area. You want one that the locals can service. The best heat source in the world doesn't help you if no one has parts and no one can service it.
Preferably, you should have a local pro provide and install at least the boiler as well. Combustion is not a place for sweat equity. The rest of the system, sure, but not that gas line or boiler set up.
Whatever you do, do NOT do an open direct system. Especially not on a system that size. Of course, that's a very large load and I would question how you arrived at that number.. it's pretty rare for me to see building loads that high.
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