Hudson reed radiator problem

Owls_hoot

Hi folks I bought and installed a Hudson reed radiator in an existing loop of my propane fired hydronic heating system. Other radiators on the loop are antique cast iron. When the system calls for heat and the antique radiators are too hot to touch, the Hudson reed is merely tepid, at best. The supply line, under the valve is also too hot to touch but the radiator itself is only barely warm. I don’t think it’s a question of installing a baffle or diffuser inside the radiator, because it’s not like it’s hot across the bottom and cold everywhere else, but I can’t for the life of me figure out what the problem is. I’m wondering if it’s just a crappy radiator (I spent a bundle on it) or if there could be some other issue. I’ve bled the radiator many times and drained and refilled the loop a couple of times too. Any suggestions? Thanks in advance. Sam

delcrossv

They have a bunch of styles, Which one did you buy? Seems the new one has a lot more pressure drop then the existing ones so the flow goes around it. One pipe or two pipe loop?

Owls_hoot

They call the style the “regent” it’s a column style radiator but definitely not cast iron. It’s a 2 loop (supply is One loop and return is a separate loop) but my local plumbing supplier had me use scoop tees since the lines that go to the Hudson reed are 1/2” and the lines for the rest of the loop are 3/4”. I’d have thought that would be an issue except for how hot that supply pipe below the supply valve on the radiator is so hot. Plenty of hot water at the radiator inlet, just none in the radiator itself. Hope this info helps.

delcrossv

I suspect It's a flow problem, not an air problem. I'm not a hydronics expert, but my understanding is If you have a separate return line, you shouldn't need monoflow/ scoop tees. Seems the scoop tee on the return is giving enough back pressure that you have no flow through the radiator.

Another thing to check is to see if the supply valve is operational. Sillier things have happened.

Jamie Hall

By "scoop tees" do you mean that this is a monoflow system? They are absurdly sensitive to pressure loss.

delcrossv

@Jamie Hall Form his description he put monoflow tees to this rad on a 2 pipe direct return system.

mattmia2

don't use monoflo tees on a system with separate supplies and returns, they will restrict the flow in the main and to the emitter. they could nearly stop the flow to the emitter depending on how they installed it. could also make it airbound.

Owls_hoot

Thanks for all this info. I think the rep at the supply house gave me bad info, possibly because he didn’t know, and I didn’t think to tell him, that I had a two loop system. Sounds like the answer is to take out the scoop tees (maybe the proper name for them is mono flow tees) and put in regular tees. I’ll do that as soon as the weather warms up and see if it sorts me out. Very much appreciated!

Owls_hoot

I swapped out the monoflo tees for regular tees (reducer tees because the problem radiator is 1/2” and everything else is 3/4”). Problem remains the same. Other 3 rads in the loop are hot, supply valve at problem rad is hot but the rad itself is cold. Everything has been bled. It’s almost like there’s a block at the supply valve. Any other thoughts?

Owls_hoot

I guess, reading back over delcrossv’s comment, I could check to see if my supply valve is bad. If for whatever reason the supply valve doesn’t open, then presumably the rad will reverse fill with lukewarm return water and bleed fine, is this correct?

delcrossv

Stranger things have happened. There's a restriction somewhere. The whole "hot up to the supply valve" is a clue.

Owls_hoot

I called the manufacturer, thinking to try to get a break on the replacement supply valve and they recommended an extended bleed with the return valve nearly completely closed. I’ve now bled about 7-8 gallons of water out of it that way. The radiator is warmer but it’s definitely not hot. I’ll keep posting progress, such as it is.

delcrossv

So you looked in the supply valve? I'm still thinking some sort of internal obstruction. I'd be tempted to take the rad off and put a hose attachment and a gauge on it and see what sort of back pressure you get.

Even with CI rads, with all the nooks and crannies, a simple bleed suffices. Sorry about your plight, Sam, but I think this is a pretty damning indictment of HR rads. I wonder if yours is not a more common issue.

Looking at them, I wonder if the flow path isn't serpentine rather than straight through like a 'normal" rad. That would explain why they want the long , slow bleed.

Please keep us apprised.

Owls_hoot

I haven’t looked inside the supply valve yet, just going through the steps their tech support recommends so I have a better case to try to get them to send me a free replacement supply valve - they’re like $100 new and I don’t want to pay to replace if it’s faulty. I’m going to bleed it a couple more times and see if that’s it. Their tech said it’s not uncommon to get big stuck air bubbles. And I do believe it’s because the path through the rad is small and may trap air easily. If I take the rad installation completely apart it won’t be til warmer weather I can’t afford to have that whole loop offline for long. As a side note, it’s pretty frustrating to pay premium price for a radiator that’s as “plug and play” as it gets and then to have to mess around with it to actually get it to work. In hindsight I’d have been better off tracking down a vintage one and using that, I think. The saga continues!