The Mother-In-Law House.

spotts

I'm fixing up a cute little labor house on my property for a guest house. Even with a bedroom addition it will only be 500 sq. ft. I removed the old siding and wrapped it with ½" reflective foam, New R-13 walls and R-19 ceiling, all new doors, windows, etc. About 20,000 BTU's heat loss MAX. I hate console heaters, we get too cold for a heat pump, and no-one makes a furnace that small. I'm thinking of heating it with a 50 gal. Rheem Power Vent II water heater (only 2" pvc chimney) with a water to water heat exchanger and a couple of old cast iron rads with their own pump, thermostat and flow check. Would you guys think I'd regret this? It's sure cheaper than a small boiler with a side arm heater. My only fear is their might not be enough hot water to use the whirpool tub on a real cold night.

PJO

Why not?

Size the radiation for 135F and might not have a problem. If they are pretty good size, then they will stay nice and warm while you tax the HWH for your bath.

If you did anything with more mass or storage it would better, but alas probably much more expensive. If you are really worried about the hot water, then why not get a larger hwh or put a buffer tank in for the heat...more mass?

I'm not a contractor but just wanted to start things off...other Wallies will chime in I'm sure.

Take Care, PJO

Steamhead

How about using

a very small boiler, with an indirect?

Examples- Burnham #202, net rating 27,000 BTUH

Columbia MCB-50/Utica MGB-50, net rating 36,500 BTUH

Slant/Fin Concept 21 CB-45, net rating 34,000 BTUH

Slant/Fin Prodigy wall-hung KC-45, net 33,000 BTUH

Slant/Fin Sentry S-34, net rating 25,000 BTUH

Slant/Fin Victory V-33, net rating 25,000 BTUH

And let's not forget our gracious hosts at Wetstock- Weil-McLain!

W-M AGE-45 wall-hung, net rating 33,000 BTUH

The above are just the ones I could find quickly. No doubt there are many others out there. They're all gas boilers, I couldn't locate an oil unit that small.

I would not hesitate to install equipment from any of the manufacturers listed above- they all make first-class gear. If your contractor likes a particular brand that's as good a recommendation as any.

The most important thing is the quality of the installation. For that you need a good contractor. Use the Find a Contractor page of this site to locate one near you.








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spotts

I AM a contractor....

steamhead. Just mostly a scorched air/ AC guy. But I've met Dan and understand simple things like "pumping away" and Pri/sec. piping and why you should put in a LWCO. I am thrilled when I get the opportunity to replace a boiler and fix alot of systems that are installed "out of the box" and are always full of air. I just like to bounce my ideas off you guys first. For some reason hot water homes are around 1 in 100 in my part of the country. (eastern CO) I'll call my Burnham guy now.

Art Pittaway

Couple of things

You need to count the BTU output on the rads at water heater/HX temp. Don't forget to put an expansion tank and relief on the heating side of the HX. Oversize the expansion tank and put a pressure switch and warning light on the heater side and you won't have to worry about a leaking heating system dumping gallons on the floor of a building you don't go into every day. Look at useing a brazed plate HX, more bang for the buck and great performance. You will need two pumps, think about how you want to hook them up, and what the thermostat is hooked to. A primary pump (Htr/HX)should run often (potable) so you pipe a loop with aquastat on return past the faucet and wire it in parallel to the secondary pump(HX/Rad). When the Rads need heat both pumps run but all summer only the aquastat runs to keep things from growing.
Sounds like a nice project, best wishes. Art

Steamhead

Oh, OK!

good to see you getting into some REAL heating systems! I bet you find you can use that little house as a sales tool- people will want you to make their houses as comfy. Let us know how you do!

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spotts

Oh Steamhead.

Don't yell at me. There's good money in replacing furnaces. Somebody's got to do it. I LOVE hot water heat. If you read my other post I'm doing infloor in my Dads new home (400 sq. ft. home with a 1200 sq. ft. garage!) also. I just don't do new homes.

Steamhead

There may be money in it

but I dislike installing something I would not have in my own house. I grew up with scorched-air and all its shortcomings, and you could not pay me enough to live with it again. I've never made any secret of this, and it's one reason I'm part of the Wall community.

The Dead Men- those great old-time heating men- spoke of "the gradual abandonment of the hot-air system of heating" in the 1920s and 1930s- mostly for health reasons, but also many early hot-air installations were unpredictable and inefficient (despite the detailed design criteria published by furnace makers such as Holland). Would that this trend had continued- we'd all be healthier and more comfortable.

I am always glad when someone- be it a contractor or homeowner- makes the jump from scorched-air to hydronics. Now that you've joined us on the Wall, you can't miss!

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