suggestions for small 40k load ?

Constantin

... not a water heater. The Polaris has a pretty chequered history, I'm not sure I'd risk being yet another bit of homeowner heating system roadkill. Plus, as Hot Rod reports, the thing is only rated to operate with open systems (!!!).

I like your idea of having a moderate buffer tank to supplement whatever low-mass boiler you're considering. They help whenever the heating conditions don't even meet the lowest input rating. How much benefit you will derive is as simple as varying the outdoor temp on your heat loss calculator and seeing when the house meets the minimum modulating limit.

Ideally, I'd size the in-line buffer to benefit in the warm shoulder seasons, but make it as small as possible to minimize standby losses. The buffer-tank module in Siggy's hydronic program may be of help here.

Another approach I have read about is to put the buffer in as a secondary zone and only activate it when it's of benefit (i.e. once outdoor temps go above the minimum modulation limit). That may be even more energy efficient and it'll increase system responsiveness too (less mass to heat).

I would go with a real, low-mass, modulating, condensing boiler. That's driven principally by my desire to have the right appliance do a job it was designed for, to do it efficiently, etc. The smallest T50 from HTP represents a good value for the money and should be much less troublesome to implement than a tankless water heater. Plus, it'll modulate down to 16kBTU/hr, which is probably still the lowest out there.

If the budget allows it, I think the smallest Vitodens from Viessmann is hard to beat, but it'll modulate only down to about 20kBTU or so. Probably close enough. Mike T. in Swampeast loves his, it's saved him nearly 50% on his heating bill, etc. A small GB142 from Buderus or the Ultra from Weil Mc may also be a good idea.

You may also want to look at where the electrical power in your area is coming from. In the long run, if the generation is driven by fossil fuels, your rates may rise to the point where using a HP becomes less and less attractive.

Tom G.

suggestions for small 40k load ?

What would you guys suggest as heat source for small load ?

- 40K btuh max load, w/ 150F max temp,
- system side reset via mixing valve,
- radiant (20K max) & hydroair (20K max) as supplement to HP,
- DHW / would use current new elec water heater as storage with preheat via HX (flat plate or reverse indirect).

Currently I’m thinking reverse indirect piped as primary with boiler and radiant/hydroair as secondaries. If so, could I get away ok with a cheap tankless ? Or, go ahead with a small Munchkin/TriangleTube/Trinity/other – any great pros/cons of one over the others?

Have also considered tank water heater (polaris) route but seems too cheesy. Should I reconsider ?

Thanks for any/all suggestions. Tom

Tom G.

Any other thoughts ???

I penciled some rough $$$s on various options. Without posting the $ amounts... (1) a modcon boiler w/Ergomax would be about twice the amount of (2) a tanklessHWH w/Ergomax with (3) a tankHWH(Polaris) w/flatplateHX falling in between the others. In that light, tankHWH(Polaris) is out because if I go HWH route then may as well go the cheaper tankless option. Also the tanklessHWH w/Egromax is easily upgradeable to modcon boiler. Given comparative low $ of the tankless, it may be well worth a try as i can easily upgrade later to true modcon boiler with little lost $$$s. Again this is small load (~10k-40k max) and is supplement radiant/hydroair to primary HP heat. Considering HWH route only because of the small load and it is all supplemental (not primary) load. Any thoughts or other ideas ? Thanks. Tom

Guy_6

T50

That T-50 is also capable of putting out 80,000 BTUs for a DHW indirect load when equipped with the Vision 1 package. With a 30 or even 45 gallon indirect it should perform admirably.

Wayco Wayne_2

I have

many T 50's out there working very well thatnk you. I'm a stickler for sizing boilers closely. I like to use as much of the throttling range that I can. And like Guy points out when calling for domestic hot water, it can kick it up to 80,000. It's got a rocket in it's pocket. (no way for you to stop it) Oh yeah! :P WW

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