Radiator advice - column rad?

matt80 · Dec 7, 2021

Hi all,

Recently moved into a house that appears to have some not-so-effective radiators (some are very hot so am confident no issue with the boiler).

The worst offender is an angled double radiator in a bay window (measures 450mm high and 240mm long). It barely gets hot despite the flow pipe feeling hot to the touch... I suspect it is full of gunk. Rather than spend a load of money trying to clear it and risk not being any better off I am minded to replace with a newer rad that will kick out more heat (it is quite a cold room, with bare wooden floors). I really like the look of column rads - do they throw out plenty of heat or am I best to stick to conventional radiators with fins if this is my primary concern? Obviously I will be downsizing as I cannot get one to curve around the bay, so I am looking at 500mm x 1500mm max.

Room is 4.2 x 3.7 x 2.5 and BTU calcs are coming out at 6000... but it is quite a drafty room what with the wooden floor.

Many thanks
Matt

steadyon · Dec 7, 2021

1. I assume you mean 2,400 mm long!
2. It could be a balancing issue. Have you tried balancing the whole system. Plenty of instructions on the internet.
3. Try turning all the other radiators off (TRVs or wheel head valves only, don't touch the lock shields) and see if the offender gets hot. If it does its probably a balancing issue.
4. If the offender has a TRV on it, turn it to max, remove the head (usually a knurled ring just under the head) and see if the pin moves up and down freely. Use something hard to push it down, it should come back up by itself. If it doesn't, replace the TRV.
5. If all else fails, turn off both valves on the offender, drain it and remove it - you'll need help unless you are superman. Flush through with mains water while tapping with a (protected) hammer. Turn upside down and repeat, Do it a few times.
6. If that doesn't work :
6a. You can get curved radiators. Basically you buy a straight one and get someone to curve it for you. Most independent plumbers merchants can arrange it. You will have to provide a template of the curve.
6b. Buy a new radiator. Start by working out the heat output of your existing one. Imagine it is straight and look up a similar size and type (single, double panel, with / without fins) on the Myson web site. Use that as the minimum and go for something with the same or higher output.
6c. With a traditional radiator, the convected heat (which is about 85% of the output) goes up from the radiator, hits the ceiling and "rolls round" and back down. With a vertical radiator, part of the heat output is already nearer the ceiling so doesn't have the same velocity when it hits the ceiling, and will have a slightly different circulation pattern. If it were me I's be looking for around 20% more output to counter this effect. Be aware that some vertical radiators require the flow into a specific side, and the return out of the other, whereas conventional radiators are bidirectional. As presumably you can't have vertical radiators in the bay, you will have pipework changes anyway and can allow for this.

matt80 · Dec 7, 2021

steadyon said:
1. I assume you mean 2,400 mm long!
2. It could be a balancing issue. Have you tried balancing the whole system. Plenty of instructions on the internet.
3. Try turning all the other radiators off (TRVs or wheel head valves only, don't touch the lock shields) and see if the offender gets hot. If it does its probably a balancing issue.
4. If the offender has a TRV on it, turn it to max, remove the head (usually a knurled ring just under the head) and see if the pin moves up and down freely. Use something hard to push it down, it should come back up by itself. If it doesn't, replace the TRV.
5. If all else fails, turn off both valves on the offender, drain it and remove it - you'll need help unless you are superman. Flush through with mains water while tapping with a (protected) hammer. Turn upside down and repeat, Do it a few times.
6. If that doesn't work :
6a. You can get curved radiators. Basically you buy a straight one and get someone to curve it for you. Most independent plumbers merchants can arrange it. You will have to provide a template of the curve.
6b. Buy a new radiator. Start by working out the heat output of your existing one. Imagine it is straight and look up a similar size and type (single, double panel, with / without fins) on the Myson web site. Use that as the minimum and go for something with the same or higher output.
6c. With a traditional radiator, the convected heat (which is about 85% of the output) goes up from the radiator, hits the ceiling and "rolls round" and back down. With a vertical radiator, part of the heat output is already nearer the ceiling so doesn't have the same velocity when it hits the ceiling, and will have a slightly different circulation pattern. If it were me I's be looking for around 20% more output to counter this effect. Be aware that some vertical radiators require the flow into a specific side, and the return out of the other, whereas conventional radiators are bidirectional. As presumably you can't have vertical radiators in the bay, you will have pipework changes anyway and can allow for this.

Hi, thanks for taking the time to reply. I have already tried the things you suggested - balancing, isolating, checking TRV.

Am slightly nervous of taking it off as I am paranoid the valves won't work properly and will not fully stop all the water!

When I say column rad I dont mean the vertical ones, I mean standard dimensions but made up of vertical columns a bit like the Victorian ones.

matt80 · Dec 8, 2021

steadyon said:
1. I assume you mean 2,400 mm long!
2. It could be a balancing issue. Have you tried balancing the whole system. Plenty of instructions on the internet.
3. Try turning all the other radiators off (TRVs or wheel head valves only, don't touch the lock shields) and see if the offender gets hot. If it does its probably a balancing issue.
4. If the offender has a TRV on it, turn it to max, remove the head (usually a knurled ring just under the head) and see if the pin moves up and down freely. Use something hard to push it down, it should come back up by itself. If it doesn't, replace the TRV.
5. If all else fails, turn off both valves on the offender, drain it and remove it - you'll need help unless you are superman. Flush through with mains water while tapping with a (protected) hammer. Turn upside down and repeat, Do it a few times.
6. If that doesn't work :
6a. You can get curved radiators. Basically you buy a straight one and get someone to curve it for you. Most independent plumbers merchants can arrange it. You will have to provide a template of the curve.
6b. Buy a new radiator. Start by working out the heat output of your existing one. Imagine it is straight and look up a similar size and type (single, double panel, with / without fins) on the Myson web site. Use that as the minimum and go for something with the same or higher output.
6c. With a traditional radiator, the convected heat (which is about 85% of the output) goes up from the radiator, hits the ceiling and "rolls round" and back down. With a vertical radiator, part of the heat output is already nearer the ceiling so doesn't have the same velocity when it hits the ceiling, and will have a slightly different circulation pattern. If it were me I's be looking for around 20% more output to counter this effect. Be aware that some vertical radiators require the flow into a specific side, and the return out of the other, whereas conventional radiators are bidirectional. As presumably you can't have vertical radiators in the bay, you will have pipework changes anyway and can allow for this.

Ok, so have been on YouTube and I reckon taking the rad off is doable so will try and flush it through. Whilst I'm at it I will replace the valves... The lockshield appears to be a non standard size going into the rad... Certainly isn't half inch, any advice on how to replace? See photo

matt80 · Dec 8, 2021

Another photo

Basher · Dec 8, 2021

I think that's a 1/2" tail In the rad. Distance across flats typically about 1.25".
Remember 1/2" bsp is almost exactly 21mm across external thread, 18.6mm inside thread.

You may find getting the old tail out is fraught. If the valve is not leaking I'd live with it!

matt80 · Dec 8, 2021

Basher said:
I think that's a 1/2" tail In the rad. Distance across flats depends on the design of the valve. (Mine are 1.25")
Remember 1/2" bsp is almost exactly 21mm across external thread, 18.6mm inside thread.

Ah ok, forgot 1/2 inch isnt the outside diameter. So a standard valve should be ok to replace this with? I've seen talk of needing some sort of extension for imperial rads, is this something i need to worry about?

Basher · Dec 8, 2021

matt80 said:
So a standard valve should be ok to replace this with?

Yes

matt80 said:
I've seen talk of needing some sort of extension for imperial rads, is this something i need to worry about?

I think that may be relating to the length (ie end to end) of a new metric radiator not matching the length of an imperial one being replaced. So extensions may be needed. If you are going to put the same rad back, no issue.

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Radiator advice - column rad?

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