I've got a 100 year old 2 story house with radiator hot water heat (not steam) and forced air A\C.  To help with heating \ cooling, I had the outside walls gutted on the 2nd floor so Icynene insulation and new windows could be put in.  Now the walls are back in.  That means the radiators on the 2nd floor are a bit oversized for the needs.

I really want to go geo, and I really want to get the tax credit.  I'm willing to accept less than optimal hot water heat in the radiator and to use forced air heating as a supplement on the coldest days.  Water Furnace Synergy 3D is the closest I can find.  It is set up for radiant floor, forced air heat, forced air A\C, and gets the tax credit. 

Is it silly to think about tying the unit to radiators instead of radiant floors?  Does the unit have enough water flow?  is there another choice?

Is it silly to think about tying the unit to radiators instead of radiant floors?  Does the unit have enough water flow?  is there another choice?


Geo will give you about 120F water temp. The Synergy might keep up in milder weather that depends on load and radiator size. The unit can only one thing at a time, hot water or forced air.

The unit is tied to a buffer tank and pumped from there to the radiators (field supplied pump).

Get a proper heat load to see what the rads will do at 120F.

Other choice is to add or replace rads.

Waterflow won't be the issue, it'll be temperature.

If you have iron radiators they are often oversized particularly on second floors where people slept with windows open due to "night death" (carbon monoxide poisoning before folks were dilligent about exhaust systems).
Lower temperatures will reduce output, but if you don't have enough many alternatives are available.
Good Luck,
Joe

Thats to all who respnded. I've talked to two local geo guys at fairs \ open houses about the idea in general. Not getting down to numbers yet, as I hate to waste their time \ try their patience. One thought that the idea was not worth even considering. The other was more circumspect. I've dealt with the secon dealer before, and I think if I push it they will bid on whatever I ask. Your response give me confidence that heat load will tell me if I should push forward, or just drop it. I'll need a heat load no matter what I do.

I've been doing "google" searches on and off for the past year on the geo topic. It suprises me that I never came across this site until yesterday. Very happy to have found it.

Rule of thumb geothermal and radiators. Try as we might, we've never been able to make existing radiators work with geo. There are new low temp radiators (Runtle Systems) that can work with the 120F water produced by geo. If you opt to change the radiators, then you might consider a warm air system.

Paul
Total Green Geo
www.TotalGreenIntl.com

Posted By glien on 26 Feb 2010 09:42 AM
I'll need a heat load no matter what I do............

You also need a radiation calculation. Your existing radiators have a measurable capacity regardless of entering water temp.
So you not only figure out what the home's heat loss is you also figure out How much is met by the exising radiation and how you wish to make up the difference.
j