I'm going to run the dyno coolant water through the infloor heating system... in the summer I'll just re-route it outside to a big radiator, in the winter I'm not throwing thousands of BTU's out the window...

I assume you are using one of the plastic tubing/pipe products embedded in the floor?

Here in Massachusetts whole neighborhoods of houses built with copper in a floor slab back in the 70s are now having problems.
I'm not sure if it's something to do with long term expansion/contraction cycles, or our water just eating the copper and solder, or even a craftsmanship issue.
Folks are just converting to another heating type and abandoning the embedded system.

SWR wrote:I'm going to run the dyno coolant water through the infloor heating system... in the summer I'll just re-route it outside to a big radiator, in the winter I'm not throwing thousands of BTU's out the window...

Love It!

A friend of mine built his 1800sq ft attached garaged with floor heat and a 50 gal powervent water heater. He only kept it around 62 but it was costing him $3-500 a month. He switched to a wall mounted flash heater and it lowered his monthly costs. I think it would be nice but still have a small furnace to warm the air and circulate it.

Dan Timberlake wrote:I assume you are using one of the plastic tubing/pipe products embedded in the floor?

Here in Massachusetts whole neighborhoods of houses built with copper in a floor slab back in the 70s are now having problems.
I'm not sure if it's something to do with long term expansion/contraction cycles, or our water just eating the copper and solder, or even a craftsmanship issue.
Folks are just converting to another heating type and abandoning the embedded system.

I'm keeping my fingers crossed, but my daughter's house was built in the late 1940s with copper in the floor and it's still working.

We used PEX tubing when we did ours about fifteen years ago and it's supposed to last longer than we do.

Dan Timberlake wrote:I assume you are using one of the plastic tubing/pipe products embedded in the floor?

Yes. I could have got a little closer for the photo, but you can see orange pipe.

SWR wrote:I'm going to run the dyno coolant water through the infloor heating system... in the summer I'll just re-route it outside to a big radiator, in the winter I'm not throwing thousands of BTU's out the window...

The in floor radiant does a fabulous job at heating up the dirt under your slab! Costs a bit to get that done in the form of BTU's and fuel to make em. I have been doing real well with inexpensive hydronic baseboard heaters and a supplemental forced air unit to break the chill in the room. The baseboard units in my 2600sqft shop (metal building) cost me about $125.00 a month to keep things at 65 degrees. The system is flexible enough that I can move the units around with some elementary re-plumbing to accommodate changes in the shop layout over the years. These are just the inexpensive Slant Fin brand units requiring only an occasional cleaning of the fins to work really well. The boiler I use is the forced vent hot water heater unit. I like to mount them in proximity of the larger pieces of equipment in the shop so that I can leverage the thermal mass of these machines. Once they are warm, the boiler seems to cycle on and off much more infrequently.

Man, this could not have popped up at a better time.
Most around here put down 1 to 2" of foam insualtion, vapor barrier, then tubing and concrete. If not, yup... you will contribute to global warming. HAHAHA
I was planning on putting in the PEX tubing.... it is not hugely expensive. My next thought was to do a solar hot water thing....I could build one relatively cheap. I have a waste oil furnace.... if the solar hot water doesn't keep up. I have tons of wood, so an outdoor wood furnace/ boiler would be possible...
The solar hot water would require trhe least amount of maintenance. Turn on pump, thermostat, pump off.
Wags

Keep the concrete at 2" above the PEX tubing with good underlay insulation and you are good. It does matter the prep in insulating the ground and more so the sides has to the effect on how the system works.

100# water temp should be all you need to make it way more efficient than a forced air equivalent.

SWR wrote:I'm going to run the dyno coolant water through the infloor heating system... in the summer I'll just re-route it outside to a big radiator, in the winter I'm not throwing thousands of BTU's out the window...

Great idea! How hot is the water from the dyno. Could you use the dyno heat to make your domestic hot water in summer too?

The underfloor heat loss issue aside [been covered], on the electric DHW tanks, elec "boilers" etc that have been used to heat the floor: Some guys seem to get caught up in the fact that the slab temp need not be that high. It seems that therefore, they somehow think that an elec tank will do it with ease. It will, but in most parts, elec is the most expensive way to heat the water. It is hard to make some guys understand that it still takes X number of btu to heat the space, period, and elec resistance heat is usually the most expensive choice.

Fwiw, imo, a properly sized boiler is the best choice, natgas if you have it. . The boiler is usually run at it's normal operating temp, and a heat exchanger is and mixing valve is used to give the floor loop the proper temp for the floor. Until the slab heats back up in the morning, a small typical ceiling mounted fan/coil or two can give you quick heat in the morning, using water right from the boiler [not mixed down].

af2 wrote:Keep the concrete at 2" above the PEX tubing with good underlay insulation and you are good. It does matter the prep in insulating the ground and more so the sides has to the effect on how the system works.

100# water temp should be all you need to make it way more efficient than a forced air equivalent.

I came up with Polyiso something for floor insulation. It is 1.75 thick, so an R10 ish.
Side of slab is against 2x6 wolmaized.... This is a big heat loss? I surely can insulate it... no concrete yet.
"Keep concrete at 2" above Pex tubing...." How critical is this? With insulation below slab I would not have thought much about this.
Thanks
Wags

SWR wrote:I'm going to run the dyno coolant water through the infloor heating system... in the summer I'll just re-route it outside to a big radiator, in the winter I'm not throwing thousands of BTU's out the window...

Great idea! How hot is the water from the dyno. Could you use the dyno heat to make your domestic hot water in summer too?

The underfloor heat loss issue aside [been covered], on the electric DHW tanks, elec "boilers" etc that have been used to heat the floor: Some guys seem to get caught up in the fact that the slab temp need not be that high. It seems that therefore, they somehow think that an elec tank will do it with ease. It will, but in most parts, elec is the most expensive way to heat the water. It is hard to make some guys understand that it still takes X number of btu to heat the space, period, and elec resistance heat is usually the most expensive choice.

Fwiw, imo, a properly sized boiler is the best choice, natgas if you have it. . The boiler is usually run at it's normal operating temp, and a heat exchanger is and mixing valve is used to give the floor loop the proper temp for the floor. Until the slab heats back up in the morning, a small typical ceiling mounted fan/coil or two can give you quick heat in the morning, using water right from the boiler [not mixed down].

Dave

p.s. - "boilers" heat water, furnaces heat air.....

I do a bit of endurance engines that will be tested in loooong slow pulls with everything up to actual running temps of near to 200ºF, so I guess it will be a fair bit of excess heat. How hot it will make the concrete, I do not know, just thinking that anything helps in -20ºC/-4ºF outside temps. Besides, a concrete floor at 60ºF is better than the same floor at 40º, especially if you're sitting on it fixing your DD's brakes or whatever.

And I'll make a waste oil burner for the rest of the BTU's needed. That can also be made to heat a big insulated water tank, like a couple thousand liters or 500 gallon one - the Swedes do that with wood - and that holds the heat for almost a week before it needs reheating. Youtube the burner, it's dead simple and you save a buck getting rid of your last oil change.

Might even hook the burner system up to the dyno water through a heat exchanger, so I can pre-heat the engine.. so many possibilities, so little time..