Hydronic radiant: how do I evaluate H-E tank vs tankless systems?
Hello GBA forum,
I’m a homeowner who has just lost a debate with my wife over the new heat source to replace our ancient furnace. She wants radiant. I wanted a high-heat mini-split. The ceiling drywall in our basement is currently down so a radiant installation won’t require a lot of demolition. Since she is my wife, she has won the day. I’m now trying to educate myself for a closed-system between-joist hydronic radiant installation. I’ll do this myself with a lot of help from youtube and several books I’ve just purchased on Amazon. I plan to do this over the course of the winter so that I can test the performance before I rip out our forced air old system.
With that said, I have several questions for which I’m hoping to receive guidance:
1) In a closed-system, what is the best way to evaluate and select the best heat source. The options I am considering are A) a *High-Efficiency* tankless (93%) or B) a H-E tank water heater (95%). Both claim to be H-E, does that make the comparison apples-apples?
2) Are there trade-offs in going with one vs the other (other than the 2% efficiency difference)? Reliability, performance, noise (I’m assuming a tankless will be on a lot), etc?
3) Tangentially related. Any thoughts/suggestions on heating a finished basement with a mixed-bag of insulation (walls are R-10 XPS but floor is only R-3). My thought is to have two layers of pex between the joists – one “pointing” up, one down. The flooring is just installed so floor-based heat is not an option. I need heat the basement either from the ceiling or perhaps via supplemental electric on walls.
We live in Chicago, zone 5. The house is a 2,500 sqft, pretty-well insulated/sealed ranch (R-20 walls, R-50 ceiling, lots of crawling around to air-seal). We have a finished basement that will also need to be heated. And we are a family of 5.
If you want more details, I’m happy to provide. I wanted to keep this post relatively short.
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