Towel Radiator

Paul Pollets

Are you "pumping away" from the expansion tank on the supply? What size pump??

If you're trying to run the TBW on a gravity system....Not!!

Sometimes increasing the pump 1 size at the boiler will get the needed circulation to the TBW...IF you're "pumping away" from the exp. tank.

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RJM_2

Towel Radiator Installation

We had a contractor remodel our upstairs bathroom in a 1920's house. The house has hot water radiator heat system with a circulating pump. Never had any problems with any of the old radiators in the house (just need to bleed some air occasionally). The contractor replaced the old cast iron radiator in the bathroom with a Runtal towel radiator. When I tried to run the heating system and see how it worked after installation, all radiators in the house heated up nicely except the new towel radiatior which had no heat at all. I opened the bleed valve at the top and NO air came out, only cool water. I bled about two buckets of water out through the radiator and finally started to get a little hot water to it. I stopped bleeding water out at this point and waited. The towel radiator never continued to heat up and actually stayed cool. I tried firing up the system again the next day and again all radiators except the new towel radiator warmed up quickly. The towel radiator was installed along a different wall than the old cast iron radiator so the contractor tied into the existing feed and return pipes and ran new copper pipes under the floor and up the new wall. The diameter of the new copper pipes is fairly small (3/4" down to 1/2") and there are now a number of new elbows in the feed and return piping. Additionally, the supply piping in the wall actually makes a loop that goes higher than the inlet of the radiator before it enters near the bottom (seems like a potential location for an air trap). It appears to me that flow to the new radiator is restricted and therefore all the hot water is simply following the path of least resistance through the rest of the system (essentially bypassing the new towel radiator). Can anyone offer some advice. I would like to get the contractor back in to fix the problem properly. I am not confident that the contractor understands the proper installation. Thanks.

Big Ed

Traps

I believe you figured out the problem with the traps. Too late to repipe? Try adding a set of purge valves on the base of a riser to purge the traps.

P.S. Did someone figured the towel warmer will produce the same heat output as the old radiator ?

[Deleted User]

Water is like my ex brother in law...

Wet, lazy and stupid. It ALWAYS wants to follow the path of least resistance. When comparing the flow pressure drop of the large standing cast iron radiators to the pressure drop of the towel rack, you're looking at the difference between a worms digestive tract versus a railroad tunnel.

Like my ex B.I.L., you have to FORCE the water to go where YOU want it to go, and not allow it to go where IT wants to go.

This means having to add a small circulator to the circuit served by the rack. It also means needing to add a means of telling the pump when it should be on and off. A simple strap on aquastat connected to the old supply main would probably suffice.

Now that the whole house is finished, it is probably not gonna be a simple process.

Maybe, instead of a hydronic rack, you can convince your contractor of his wrong doings, and make him give you an electric plug in model instead. THey make them in 120 volt configurations...

Wish we had better news, but hydraulics is hydraulics, and there is no way to balance out your system to favor the worm hole.

Best if luck.

ME

RJM_2

Towel Radiator

Thanks for the reply. I believe the rating for heat output on the new towel radiator is similar to or higher than that of the old radiator.
It is not too late to repipe, although it would involve knocking out the palster on some walls and part of our kitchen ceiling.
I am not clear on the purge valves at the base of the riser idea. Is the base of the riser the point where the supply pipe to this radiator branches off the main in the basement? How would a valve down in the basement purge air from a pipe on the second floor? Sorry, this is far from being my area of expertise.
Am I correct in my understanding that the best thing to do would be to repipe the unit and maximize the supply and return pipe size while avoiding any loops that could function as traps? All pipes should pitch down away from the inlet and outlet of the radiator?
Thanks again.

Derek Moore

I agree

Yes Mark that will definitely work with a circ and an aquastat. I usually use 2 monoflow tees one facing each way so its pushing and pulling. as long as the piping is continually rising, or has a drain ,on that circuit, for purging to get ALL of the air out it will make the trip up the worm hole (lol) by creating negative pressure with the venturi

PS I once had an old monoflow tee (11/4 x 3/4) that was clogged solid so if there is an old one, check it, even a pump can't pump through gunk.

just a thought

by the way I had a chuckle at the ex BL comparison.

Derek Moore

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Weezbo

flip the pump....

if there are valveas on the system on both sides of the circ. then instead of running the boiler just run the pump....now if you get flow meaning the heat comes out of the boiler thru the towel warmer you may have less of a problem fixing it than you thought....

Weezbo

Hmmm....