Slow Floor Heat Loop

[Rudy]

My 18 year old wash has a floor heat circuit that runs cooler than the rest. The "circuit setter" is completely open, and ice builds up on busy days.

I've verified (using a point and shoot thermometer) that the return line on this circuit is about 15 degrees cooler than the rest.

I closed all of the other loops, forcing fluid to "push" any air out of the loop. There's no heaving or other mechanical indication of problem....so I'm stumped.

Any reccomendations? Why would it work correctly for years, and then slow down? Could a little Taco pump be plumbed inline to help?

 

[2Biz]

Is the flow control for that bay a ball valve or gate valve. If its a gate valve, I've seen the connection to the "Gate" break off. It might apear that you are turning it on when in fact it is staying shut. You might try taking the return line off and see if you are getting any return coolant?

 

[PaulLovesJamie]

the flow control valve for that bay is probably stuck or has a piece of dirt in it

 

[Rudy]

The flow control valve is made of plastic with 4 stainless screws in the corners that hold it together. I tried to disassemble it.....but there's a problem. The manifold is built in a box that's below the grade of the floor. The pex tubes enter straight from the slab, directly into the manifold. There's only about 5 inches of exposed tubing to "work" with....therefore there's not enough "play" to remove the compression fitting. My only option would to cut the line to remove the fitting, and then splice back a loop for reattachment. Do I dare do this????

 

[PaulLovesJamie]

I'm not certain that this is your problem, but that is exactly the symptoms I had a couple years ago.

My only option would to cut the line to remove the fitting, and then splice back a loop for reattachment. Do I dare do this????

that would be a last resort for me...

I'd tap on it a few times with the head of a screwdriver, see if I could jar dirt loose. Next thing I'd do is try to take those 4 screws out & see if I could clean it out. Be sure to have some antifreeze on hand to refill.

My flow control valves are also grey plastic with 4 SS screws, but there's also a 5th screw in the center. Simply taking out then replacing that 5th screw is what worked for me, I didnt actually have to take mine apart.

 

[Rudy]

I drained my system and was able to remove the "system setter" from the slow return line. There is a ball valve, which appeared to be clean and unobstructed. I was hoping to find something which would have indicated my problem.

While it was apart, I isolated every other loop, and used a compressed air hose to backfeed the return line with air after removing the fill port of the fluid tank.

I eventually heard air coming out of the fluid tank after a while. Although there was flow, it felt like there was considerable resistance.

The reason I backfed the return line was because it was going to be very, very difficult to unhook the feed line from the manifold.

Here's my question.....

How much resistance would the circulating pump provide in this scenario?

I was essentially blowing compressed air into a disconnected loops return line, through the loop, into the feed manifold, and into the exit of the circulating pump and into the fluid tank above the pump.

Is the resistance I felt normal....or indicative of a pinched/collapsed line?

 

[robtl]

Look at the bay floor real good to make sure the concrete has not cracked and shifted in a spot to pinch of a loop also look at the slab at the wall to see if it has heaped or droped during this changing weather.
If you can get to the supply line that feeds the loops the bad bay might be the last one on the header and not getting enough flow, try switching the bays around on the supply manifold and see it follows the switch.
I would also throttle down the other bays to about 75% open with bad bay at 100% open to see if that helps.

 

[Jeff_L]

I just had my floor heat pump apart the other day. It appears it would provide a lot of resistance the way you were feeding the air. Do it on the return of another loop and see if you get the same results.

Either way, it does sound as if there is something restricting the flow in that loop.