Hydronic Radiant From Water Heater Coil
I am considering adding supplemental hydronic radiant heat in (mostly) new construction. It would be a lower operating cost alternative to using electric heat mats under kitchen and bathroom tile, and in a sunroom that may feel chilly in the winter because it has lots of windows. The radiant would not be the main heat source, but used to make the spaces and tile feel more comfortable.
The water heater is being replaced so I’m considering something like the Bradford White CombiCore that has a separate hydronic core that doesn’t allow the potable and hydronic systems to mix, assuming no leaks. But I have not heard great things about this setup. Are there other heaters that might work, or is this a bad approach considering efficiency and control of the hydronic system?
Thanks,
Billy
Replies
Greetings Billy,
This post, in response to your question, will bump the thread through the 'recent discussion' listing again which will increase it's viewing.
Perhaps it will catch someone's attention that can help you with advice.
Cheers
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Hi Rez,
I've changed my approach to using a Triangle Tube mod-con boiler for hydronic radiant, and I am considering using one of their indirect hot water heaters. This might be a good way to go for efficiency, and the stainless tank in the indirect water heater should last a long time.
Does anyone have experience with indirect water heaters for DHW, and is this a good approach if we're already installing a condensing boiler for hydronic radiant?
Billy
What do you mean indirect water heater ... off the boiler for space heat? If you use a boiler for space heat and then have a heat exchanger for the DHW, that is not a good combination ... as you have to run your space heat boiler all summer to provide DHW. Basic rule of energy ... separate them. BTW ... I used the CombiCore for DHW and radiant floor. I'm not saying this was a good or the best idea. It does work. Maybe too much for both. ... Not sure. The concept is OK, though. Ideally they should be separate systems, though I suppose.
Seems you want to do hydronic radiant floors but you aren't really committed ... to the whole house. Seems a VERY expensive option for doing a couple of baths and the sunspace. Is the sunspace poorly designed that you feel compelled to put energy into the floor? Do the occupants feel compelled to heavily occupy it during the heating season? I designed a passive solar sunspace using Heat Mirror glass ... unheated. It never got below 55 in there even when it was VERY cold outside (well below 10 degF. The plants loved it ... had to hack them back every year 'cause they did so well.
Supplementing heat in the bath w/ radiant ... seems expensive, but your concept is solid ... warm floors mean comfort ... then you could likely turn off the air to the room. Again, though, a lot of expense in hydronics for a couple of areas in the house. Just trying to add some dialogue and food for thought ... maybe it will trigger more conversation/input by others as well.
The hydronic radiant will be almost all of the house (different from the first post where I was considering only some areas).
Why buy two mod-con boilers if I can do both radiant and DHW on separate water systems with one boiler without losing much efficiency?
Billy
The primary reason NOT to combine them is efficiency ... using one large boiler all year is (arguably) less efficient than using separate boilers. But considering the small standby heat loss of a DHW heater, it's probably no big deal. In commercial buildings, the DHW load is often tiny compared to the 2 story boiler you use for heating, so the practice is generally frowned upon. In residential, using the combi core is probably a fine idea with minor ramifications in efficiency. I did find out that the combi core wasn't elligible for rebates ... I originally thought that since it used PVC flue, that it was high efficiency (i.e. above 90%), but I found out after I purchased it that it wasn't ... only around 85% efficient, but still using the plastic flue pipe. Not sure if there are more efficient water heaters using the HX inside them or not.
The triangle tube is a condensing boiler. Good for this app.
Using an indirect tank with the Triangle is a great combination. Hard to get any better.
Thanks, Rich. I appreciate the feedback.
Billy
The Polaris system has had a good reputation for this, too. Much more expensive than the Combi Core, though (higher efficiency, too ... maybe much higher quality as well). Not sure who makes the Polaris (sounds like a snowmobile company :) ).