in floor heat

Rob_10

Simple in floor heat because I'm a simple kinda guy. I'm new to hydronic heating and would like some help. I'm putting an in floor heating system in a garage.The intial design was done by my local wholesaler ( heatloss, number of loops , pump spec). Heat source is going to be a 30k BTU water heater. Owner primarily just wants to keep garage from freezing but will occasionally be workin in it. Now my question is,( being that I am simple )what would the easiest method of control be? Thermostat brings on pump on demand of heat? Tubing is in concrete slab, is there a max floor temp? ( 85'f ? ) What temp should I set the water heater at? ( lowest possible temp that will maintain slab temp? ) Or should I set the temp higher and use a mixing valve to maintain the loop temperature? Not quite sure what to do, but I'm sure you guys can help. Is there a canadian distributor of Dan's books? What are some good basic books to get for someone who is just starting out in hydronics?

Richard

IN-FLOOR HEAT

Need more information to be able to answer your questions. Are you using blue board under the heat tubing. What size tubing are you using, what is the spacing you are using. Note pumping cold water back to a w/h is going to cool down the w/h. Would be concern if the water heater would keep up
Thank
Richard

Jed_2

Water Temp, Delta T

If your wholesaler did the heatloss analysis, with loops, pump, etc., then they have the SWT, surface temp, flow rate per loop, and total flow rate. You need to get it from them! They did it.

Jed

Greg Swob

As I see it,

the use of a water heater as a source for hydronic heating is pretty limited. Two garage heat loss calcs I did in our region recently resulted in about 27 mBtu for one; 58 mBtu for the other of heat output needed. These calcs were specific to the two projects I looked at and are not indicitive that any one garage needs XXX mBtu of heat. That said, considering the efficiency of an average run of the mill water heater is stated to be about 65%, maybe 75% depending upon model, etc.), now were are looking at a 30 - 40 gal WH output of only +/- 22mBtu. What about standby losses and perhaps there are other indicators to factor in? Then, listed products only should be used. Perhaps when low installation budget for a very small heat load, and long term maintenance, fuel and equipment replacement costs are not to be factored would I consider a water heater as the heart of a system. That said, we have a few systems such in place, but very few. For those of you who install many water heaters as system heat sources I would appreciate any success stories (long term experience preferably). Maybe we're missing something here - I am very open-minded, but... Thanks - Greg

Mark_25

Perhaps gas and electric water heaters have lower inputs, except the Polaris, but a typical oil water heater starts at 70Mbtu input and moves up from there. I know most don't want to spend the money on oil appliances, but they do make sense in some installations.