No Heat in Sun Room underfloor

Justin Gavin

I have a stumper for you.

I was at a job which had originally a conventional boiler supplying heat to an indirect hot water heater, basement baseboard and underfloor in a sunroom. There was only one loop in the system with zone valves on the return side of the boiler. The underfloor was using a 4-way mixing valve (no actuater) to supply heat to the loop and protect the old boiler. The sunroom is using Heatway hose in the sunroom.

They don't use the room often because they have a hot tub in the room that adds enough heat when in use.

Last year they replaced the boiler with a 80 munchkin. On X-mas eve they tried to heat up the room and got no where. I was thinking that the 4 way valve wasn't working properly because the Munckin modulates.

I took out the 4-way, added a 3 way thermostatic valve with a Taco 007 with zone control and I am getting 120 to the radiant loop but only about 80 coming back.

They are no better off than they were before and I am stumped.

I already checked flow through the radiant loops and there is flow through all 3 loops.

Anyone out there have any ideas?

Please let know if you do.

Best Regards,

Justin Gavin

mph

Sunroom

With a 40 degree delta t you're either dumping a bunch of heat somewhere (so it may take a day or more to bring it up to temp) or your flow rate is way down. How long has the zone been running? Is there insulation under the floor? Did this zone ever work?

Jeff

Justin Gavin

More info

Well the loop has been running for 2 days now. They never had a problem when they were using the conventional boiiler.

I think it has something to do with the way the Munchkin modulates.

Any ideas?

Thanks,

Justin

kevin coppinger_3

how long

are the loops? Is the circ sized right? What is the heat loos and is there enough tube/hose in the floor? Is it entran 2 hose? Is it possible that when the system was taken down w/ the new boiler that purging caused some hose collapse or plug? Could you flush it out w/ a cleaner? kpc

hr

How large is

the hot tub. Could it be covering too much of your floor space (heat emmiter)? With a covered insulated tub, any tube below that will not be able to emit much heat, called heat flux. Divide out the area the tub covers and see what square footage you have left for heating the room.

Oh yeah, make sure the ball valves at the Heatway manifolds are open completly

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Contractor"

mph

Water temps

If that 120 supply and 80 degree return are constant the entire time that zone is on, then the boiler modulation would have nothing to do with it. If the zone worked in the past (did you witness this or could it be the homeowner's faulty memory?) then something else has changed.

Jeff

Mike T., Swampeast MO

If you're certain you're getting proper flow through the radiant loops I think you might find the answer by combining all of these replies.

Floor cold from long period of non-operation. Hefty delta t (40°). With temps you supplied average is about 100°. Spa that possibly covers a lot of the floor reducing possible output. "Sun" room so lots of glass and lots of heat loss.

Put that all together and your 120° supply temp provided by the mixing valve is likely inadequate to both supply the heat being lost AND raise the temperature of the floor in a reasonable period of time.

Perhaps a two-stage thermostat to boost the temp supplied by the 3-way valve when air temp is more than a couple of degrees below desired setpoint?

Duncan_9

Checked the flow

Justin... Exactly HOW did you check the flow?

120°F water circulating with a 40°F temperature drop for two days should throw SOME heat into the floor! No flow, no heat. It's possible the 80° you're seeing at the return is just thermosiphoning (heat migration through a single pipe). A bad circ out of the box might act like you describe, but...

Need to know how you checked the flow.

John Ruhnke1

Its most likely the pump...........

A 007 is not a good pump choice for long radiant loops. I never use it. It has a very low head. Thus your flow rates are lower then needed. Which explains the higher delta T. You may need to install a 008 or 009. It is very important to take some training before fixing or installing radiant projects. Buy some good books or take some seminars.

JR

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Contractor"