Help with radiant floor heat

[PWC Repair]

Here is a pic of my current plan. I already have the water heater, ex tank, fan coil, manifolds, and of course tubing in the floor. Our frost line here in Northern Arkansas is 18" and about 1/2 my floor is below that cause I cut into the hillside. 1" styrofoam under the concrete with reflective foil backing facing down. I plan on using only the floor OR the fan coil but NOT both at once, hence the shutoffs at the Tees. Just wanting to keep the shop 55-60 but possibly sometimes blow hot air directly towards work area via the fan coil. I will use a standard thermostat of some sort and a couple common relays for controlling the pumps. My questions are......Am I missing anything component wise? Which pump do I need for the main floor tubing?

 

[Jackfre]

Not sure what the mix ratio will be, but you are going to be in for a lot of glycol on that system. I would drop the glycol and run water. Glycol seems to offer advantages, but it must be monitored and maintained or it can screw up a system over time. It is not a "one and done" type component. If you feel the slab absolutely has to have it add a small plate hx and treat only the slab/AH portion. Before I used glycol I'd install a supplemental DV heater for back-up. Glycol adds to the viscosity of the fluid and requires more circulator. Component wise you might want to consider a Watts pressure reducing/relief combo unit on the feed.

 

[PWC Repair]

Oops!! That should say Propylene glycol mix. I had an old water source heat pump given to me and the tank has about 30 gallons in it.
This is closed loop and I plan to pressureize 10-15 psi.

 

[Jackfre]

Old HP...old glycol? Check the ph prior to putting it into your system.

 

[fitter30]

To accurately pick a pump need to know size and length of pipe. Also what type of pex is it? With or without the oxygen barrier.

 

[PWC Repair]

Yes, oxygen barrier pex. Specs are on my pic above....4 loops 1/2" 300ft each setup as a single zone.

 

[PWC Repair]

So, I'm thinking I need around a 1/25 hp pump like the Taco 007. Anybody agree with this?

 

[Copymutt]

24 yrs on a closed loop water only system.NG. One of the best investments i ever made. We get much colder here. Occasionally minus teens for several days.
I do have a hanging 35k heater also, but never needed to use it to keep the in floor from freezing. Its been bullet proof.

 

[fitter30]

1200' 1/2" pex = 11 gallons of water add another 2 gallons for boiler and fan coil 13 gallons. 4 gallons of glycol 30%. I wouldn't use used glycol because you don't know what the additives levels are. Fan coils don't put out much heat under 120*. Floor heat water temps run 5-10* over thermostat setting. Piping pex floor loops the two manifolds pipe a-b-c-d supply d-c-b-a return that will give you equal flow through the loops. To pipe system correctly with the fan coil a primary secondary loops would have done. Since the floor piping flow rate is 3.6 gpm @ 10k btu's per gallon your close to the out put of the water heater. Might just try just the floor.

 

[theoldwizard1]

You are not going to get really "hot" air off of that radiator feed by 110F water.

 

[PWC Repair]

You are not going to get really "hot" air off of that radiator feed by 110F water.

I'm used to that....I have had an R22 heat pump for the last 15 years. "Warmish" air is fine by me.

 

[86turbodsl]

If you're going to run a HX, you might look at methanol as your antifreeze. cheap and doesn't degrade like glycol. Pumps easier too. poisonous though, so take your precautions.

 

[PWC Repair]

A friend of mine gave me a Grundfos UP26-99f pump. Will this work fine on the floor or is it too much pump?

 

[fitter30]

Pump section 3.6 gpm x 11 ft head. Taco pump 008 1/25 hp

 

[PWC Repair]

Thanks, I'll see if I can trade this one for an 008. Some more hvac guys I know use that one on the Hardy outdoor wood furnace.