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Thanks, Dana. I appreciate your help!

Just wanted to bump this up. Dana, would love your opinion about the best choice out of some 100%-satisfying options.

Dana, I've got some updates and was hoping I could get your thoughts. Unfortunately, there are no contractors in the DC-area with HTP or Lochinvar expertise (at least that I've come across). The primary brands are NTI, Triangle Tube, and Viessmann. Given that none of the Triangle Tubes go...

I guess I'm just curious how any radiant floor is going to keep from short cycling unless there is a buffer tank. It looks like Uponor recommends a maximum length of 300 ft for 1/2 inch tubing. So assuming you're talking about 10 btu/sq ft applications, it seems like none of them would be...

Well, the 15 btu/sq ft was just a guesstimate on my part, but overall it sounds like the suggestion to staple to the joists is a contractor red flag. Any thoughts about the likelihood of short cycling given that the zones seem to need to be small, even with proper installation of radiant?

And, one more question - does a radiant floor increase the possibility of short cycling, since it seems like a typical radiant zone is around 300 sq ft - assuming 15 btu/sq ft, that's only about 4500 btu, which is much lower any boiler will modulate to.

I guess, would a suggestion to install radiant that way indicate a red flag for the contractor overall? Pictures of prior installations look clean, at least.

Just got a new bid and was hoping you could provide some feedback. I'd asked for a quote for retrofitted radiant in the basement joists - there are narrow-plank oak floors above. The contractor suggested stapling to the joists rather than using plates to avoid nails into the flooring and...

You're not making it easy, Dana :-) Ok, I'll keep searching for someone who can install the KHN or UFT with some degree of competence.

FWIW, they're also not super keen on ECM pumps (in relation to a question on pumping the Tx51) for reasons I can't quite fathom: There is no point using an ECM pump because we require a fixed flow rate. If they choose to use an ECM pump and set a fixed flow then the Grundfos ALPHA should work.

Sorry, to clarify, 5 therms/month rather on the summer gas use.

Yeah, I was bit surprised that the company itself was recommending a significantly larger boiler, rather than, say, the Tx81 if they really felt the 51 was too small. I can't quite figure out their reasoning for why oversizing by 100k BTU would be a good idea. That being said, the contractor...

Dana, thought you might be interested in this and wondering what your take would be. The contractor I asked to take a look recommended a TFT 110 (min fire of 22k) and contacted NTI directly when I asked about estimated heat loss. They replied that: Primary secondary is ALWAYS best practice...

For use as a primary pump, did you put the 1816 on fixed speed or constant pressure?

What are the consequences of the boiler loop being over-pumped? The Tx51 manual recommends a Grundfos 15-58 for temp rises of 25 and 35F and a 26-99 for temp rise of 20 - my understanding is that a Taco 007e would fall somewhere in this range, but I'm not sure how to best compare. I'm not...

I assume a 007e would work as well?

So, assuming P/S piping, both the NTI and Lochinvar manuals call for a Grundfos 15-58 or equivalent for the boiler loop pump. Given that this pump would presumably be operating nearly 24/7 during the heating months and that it appears to use around 60W, this seems like a huge electrical load...

Dana, one last question - it looks like the Lochinvar KHN-85 supplies a Grundfos 15-58 for the boiler circulation. It looks like even on the slowest speed, this pump uses about 60 watts. Assuming that's running 24 hours a day, that's upwards of 43 kWh per month, which seems like a lot when the...

Haha, thanks Dana. Great explanation as always. I really wish there were well-rated contractors who used HTP and Lochinvar routinely down in this neck of the woods. This seems to be largely Weil-McClain country, which doesn't get you very far.

So you don't buy Viessmann's argument that their specific boiler may operate better on low-load zones than a low-mass 10:1 boiler? In their white paper, they make a lot of noise about titrating the oxygen levels for the best possible combustion mix and that their high-mass system reduces the...