baseboard boiler now for radiant floor later

[dwassner]

Hello all. My wife and I closed on our house about two weeks ago. Per the lenders requirements the boiler must be replaced. The contractor is letting me pick it out (we are good friends). Attached is a rough map of the current baseboard system. The house is a 1966 ranch, around 1220 sq ft, natural gas, and all copper plumbing.

Energy audit facts:
-flow rate of 3124 CFM measured by blower door test (1700 is recommended, and fairly easy to achieve given the list he supplied)
-energy factor of 5.5 btu/sqft/hdd (he called this average), after "energy improvements it was 3.9 btu/sqft/hdd
-recommended boiler size of ~45k btu.

I would like to go with radiant floor in the near future (a year at the latest). I have been looking at the smallest lochinvars that are around 50-55k btu's. This is above what was suggested but the auditor didnt consider that i will be replacing the old water tank with an indirect and will be heating atleast half of the basement with baseboards, although not all the time.

So my question is: is there a boiler or size range anyone can point me towards that will work with the baseboards until the radiant is in? Also a pump size? Any other suggestions? I have roughly $3400 to spend on a unit.

Thanks

[bobboan]

What kind of radiant? Staple up floor? Slab? Both?

[dwassner]

it would have to be stapled up, the joists are exposed.

[bobboan]

it would have to be stapled up, the joists are exposed.

A mod/con boiler would be your best investment. The Lochinvar Knight WHN is an excellent boiler that can be setup to supply 3 different water temp zones.

If you use a cast iron boiler, the efficiency will be lower and more external controls will have to be added to supply the correct water temp and also to protect the boiler and chimney.

Your don't want the water temp above 120* with staple up, and it really should be designed for lower. A cast iron boiler needs to maintain a return temp of at least 140* whereas with a mod/con, the lower the return temp, the better.

Also, I'd plan on keeping some of your baseboard unless an accurate heat loss calculation would indicate that the radiant could heat the house. In most climates, it won't do it by itself. The best that a well designed radiant floor will usually produce is about 25btu's per sq. foot of heated floor. That's with plates (which are not optional).

Radiant requires a knowledgeable hydronics man or it will turnout to be a nightmare. It's not a DYI project, though you can certainly do some of the work with proper instruction and over-site.

Another word of caution: Don't use an Internet Hydronics Peddler. We have a regular business of customers who have been burned by them and I've yet to find one who knows Hydronics correctly.

Also, don't even consider using a tankless in place of a boiler (a common Internet rip off).

Again, the most important component is a good designer/installer.

[dwassner]

That is news to me I thought having the radiant would take care of it. What do others do that are in a climate like mine (upstate NY)?

[beenthere]

Might want to look for contractors on our Contractor locator map.