Some radiators not heating

Igotadose · 19-10-2023 7:46am #1

I've a few radiators, the ones furthest from the Firebird 90 heater don't get as warm as the others. System is 20 year old Firebird 90, 2 zones one for hot water tank the other the rest of the house. System gets regular maintenance. Radiators look like this:

All the restrictor valves are wide open.

I have bled the radiators several times, the one in the image is far from the boiler. Some air came out for awhile along with some nasty black gunk, but even with the 'bleed water' clear, still this radiator and the one between it and the boiler refuse to warm up.

I've checked all the radiators by bleeding them and no others had air in them except this one. Now it doesn't, but it still doesn't warm up.

Is the problem that the Firefly's just not circulating the water through the radiators hard enough? The water seems to circulate well, the rest of the radiators heat up quickly and thoroughly.

Suggestions welcome, short of tearing all the heating system out and the radiators, I don't think there's anything I can do. It could be a design problem, as the radiators in the 'residential' part of the house get toasty warm, this radiator, the one upstream from it and one other in the same non-residential area of the house (kitchen/sitting room area), don't get warm though they're not frigid as if no water got through.

10-10-20 · 19-10-2023 9:24am

Hi, it sounds like a balancing problem, or possibly a blockage due to a buildup of sludge. The restrictor valves (are they the lock-shield valves) should not all be wide open. You should partially close off the lock-sheld valve (not just the TRV valve if you have one) on the closest rads to the boiler and then work outwards until the system is able to deliver hot water to this furthest rad. I sometimes start by closing all of the rads to within about a turn of the lock-shield valve, then moderate that upwards further away from the boiler.

If that rad still doesn't get heat when the lockshields are mostly closed, then it's likely blocked by sludge (or airlocked) and you'll need a plumber to pressure purge the system.

Igotadose · 19-10-2023 10:14am

https://www.boards.ie/discussion/comment/121258024#Comment_121258024

The valves are TRV valves not lock-shield. I was thinking of a similar experiment - turn off all the residential valves and see if that pushes enough water to warm the cold radiators.

I don't think the system has any lock-shield valves in it.

10-10-20 · 19-10-2023 10:19am

https://www.boards.ie/discussion/comment/121258208#Comment_121258208

Take a photo of the feed into the rad opposite the TRV. It's probably a lock-shied, just covered-off.

Igotadose · 19-10-2023 10:33am

This is one of the radiators that isn't heating:

Other end of the same heater:

This is another heater, nearest the boiler, that works fine:

Thanks for replying to my questions!

10-10-20 · 19-10-2023 10:41am

Pull off that cream/white cap - that's the lock-shield valve!

DC999 · 19-10-2023 10:58am

+1 to sounds like a balancing issue. This is a very good and short video. It's from a trusted channel: Get More Heat From Your Radiators ~ System Balance - YouTube

Another thing worth checking is power setting what the pump is set to. That is moving the water from the boiler into the rads. Most seem to have 3 power outputs, 1,2,3 as in slow, medium high pumping force. I read that pumps lose power as they get older, plus the gunk builds in the system so it’s harder to push. Mine is and always has been at 3 since installed. So I can’t make mine pump harder. You could note what it’s set to, then increase it and see if it helps. Bear in mind it can shorten the life of the pump and will us more power. So look at balancing too. Here's a pic of our pump and it's set to 3 (the 3 lines).

Alun · 19-10-2023 11:03am

The radiator that you say isn't heating seems to be missing it's TRV head, it's just the valve itself there as far as I can see. I don't know if they default to open or closed if the head isn't present, or maybe it's just stuck I don't know.

Dr_Colossus · 20-10-2023 10:37am

https://www.boards.ie/discussion/comment/121258387#Comment_121258387

+1, they default to open so you should have heat just not able to regulate it. That said the pin/insert should be fairly free moving and you should be able push it down with a coin or something flat to ensure it's not seized/clogged.

As the fertilizer said check all the lockshield valves (opposite end) and try rebalancing the system. It could be something simple like the lockshields on the non heating radiators being nearly closed with the working rads being near fully open especially if they've never heated up correctly.

10-10-20 · 20-10-2023 10:57am

https://www.boards.ie/discussion/comment/121262278#Comment_121262278

"As the fertilizer said check all the lockshield valves"

No manure there! 😂

Igotadose · 20-10-2023 4:14pm

Thanks everyone for the advice. Between the video, and a couple of web pages, I worked out how to balance using the lock-shield valves and everything is evenly heating now. Now if I'd only known this when we moved in...

Some radiators not heating

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