Water temperature - Concrete basement vs Wood flooring

rcc147

My contractor just finished installing a new pex system in my 1880's house over two floors (basement and 1st floor):

Basement - Regular installation in concrete with tiles on top. Radiant heating works well.
1st Floor - Installed between joists under sub-floor with aluminum heat transfer plates and double insulation below. No heat at all coming up through the floor.

He used one mixer valve for this set up and set the water temperature to 110 -120 degrees saying any higher may crack the tiled floor in the basement. I told him the 1st floor was cold and he said it needed to be run for 24 hours before I noticed the heat. I just finished this 24 hour test and the floor is still cold. The hot water is definitely running through the pipes (water pump running, expansion noises, pipes at manifold are hot).

After some online research I see that water temps for pex under a wood sub-floor should be in the 140's, not in the 110's. Is this correct? Should I ask him to re-pipe the system with one mixer valve for each floor?

Thank you.

SWEI

No harm in turning the temp up to see what you get in the first floor. Was a heat loss calculation performed before installation? Do you have any photos of the plates, or at least the name of the product used?

That 4-way valve should be run by a motor to manage the water temperature based on the outdoor air temp. You may need separate mixers for each floor, or the boiler may not have been set up properly, in which case a bit of piping and some programming will do the trick. What kind of boiler is being used?

rcc147

No, he didn't do a heat loss calculation. No photos of the plates and can't recall the model. Boiler is a gas fired water system (weil McLain CGI gold 210000 btu).

SWEI

Need to begin at the beginning, with a proper heat loss calc. How many square feet is each floor, and have any envelope upgrades been done to the house (insulation, windows, etc.)? Where is it located?

We need to find out what's under that floor if at all possible. Plate type and tube spacing would be a good start.

hot_rod

what type of floor covering on the first floor? Carpet and throw rugs really put the hurt on radiant floor output. Furniture? lots of built ins lower the heat flux also.

It may just need some higher supply temperatures to the upper floor.

Tinman

When you say double insulation below, what exactly do you mean? Did he double the amount of insulation or were you referring to double bubble insulation?

RobG

Stephen Minnich said:

When you say double insulation below, what exactly do you mean? Did he double the amount of insulation or were you referring to double bubble insulation?

My thoughts exactly on the insulation. also, how thick is the subfloor? I have seen old houses with 3" of wood. What type of plates, extruded or stamped? What size tubing and how many runs per joist bay? How long are the loops? Lots of questions that need answering.

Rich_49

Lots of wives tales floating out of the Gcs lips . He is mislead on the water temp thing so maybe he also thought you should leave an air gap between the sub and the insulation . Just went through something similar with an insulation contractor who did me a favor and did it the way he does all the radiant jobs he does . Suspended tube . Heat going right out the box around the entire perimeter . That air gap thing don't work real good with joist trak plates ya know !
Are both install methods on different zones ? If they are you can run the hotter water through the slab , when the surface temp reaches its requirement for the load it should shut down the zone . Shut down = closed zone valve = no more flow = can't overheat .

rcc147

1st floor is 800 sq ft and has hardwood flooring in the living room & kitchen, tile in the kitchen and bathroom. No furniture. Pex is 1/2" double runs between joists. Insulation is 3" soundproofing x 2 , so 6" thick. Floor is probably 2" thick. Four runs of pex, 300 ft each. Basement and 1st floor are on different zones with a thermostat each.

Appreciate the responses so far.

rcc147

Also 1st floor is very well insulated - new doors and windows (low e, argon gas etc.), ceiling full of insulation.

Tinman

As was mentioned earlier, adjust the mixing valve so your supply water temperature increases. I would go 15 degrees at a time and wait til floor temperatures peak. You don't want the surface temperature of the hardwood higher than 80 degrees.

Tinman

As SWEI said, motorized mixing valve is the way to go.

SWEI

With 8" spacing and plates you should be able to make this work (assuming nothing strange there like beer can strips.) One plus: the pipe work looks clean and thoughtfully done.

The mounting ears on that 4-way valve look like an LK, but the pipe fittings are more like what Roth ships. I suspect the Belimo actuators and shaft coupler we use for the LK valves might fit it. Roth sells an ODR kit as well.

icesailor

Not to be picky, but,,, how do you get the air out of that circulator with the body standing on its head and Taco isn't found of that unless there is no other choice. Then, you make "adjustments".

I sure wish that GC's would stick to their wood butchering, and leave the technical stuff to those of us who know what we are doing.

Gary Jansen_4

Unless you are running more than 20 lbs. of system pressure, that Taco pump isn't going to last long. I'm guessing your system pressure is more like 12 lbs., which is probably all you need. In that case pump motor shaft should be in a horizontal position. If you need to reposition the pump, the junction box should be rotated to the top side. You really should have a 2nd mix valve, something like a Taco thermostatic valve and pump to maintain your 2 temperatures needed.