Some Rads Have Stopped Working.

[JackSkully]

Hi,

2 years ago I had a garage conversion done which involved adding 4 new radiators to the system and also having a new boiler fitted. Although balancing all the radiators on the full system took an age to do everything did eventually work well.

Unfortunately now 1 of these rads is working at approx. 75% capacity, another is at about 10% and the other two don't heat at all.

I have tried shutting them down together with one of the old rads which is nearest to them and opening up one at a time without success. I have also removed the thermostatic valves to check the pins are free which indeed they are. I have left these valves off in case they are sticking when in place.

I have noticed that the pipe to the thermo valve gets hot but the radiators do not and the other pipe to the "shut off valve" remains cold. ( I'm hoping this may be the key to someone who understands these things more than I)

All of the original rads in the house are functioning well.

Does anyone know what the problem maybe and what I could try to rectify the situation?

I would greatly appreciate any advice as its driving me mad at the moment!

Thanks in advance.

 

[bolshy]

Try bleeding them if you haven't done so already. If that's not the problem, you then need to shut the TRVs on all but one of the working rads in the house. Have you gently depressed the pins on the TRVs to free them? Open up each cold radiator in the conversion one at a time. See if you get any flow through them.

 

[JackSkully]

Try bleeding them if you haven't done so already. If that's not the problem, you then need to shut the TRVs on all but one of the working rads in the house. Have you gently depressed the pins on the TRVs to free them? Open up each cold radiator in the conversion one at a time. See if you get any flow through them.

Thanks for your reply.

I have bled them but they seem ok in that department as there was no air escaping. Also the TRV pins are free. My reluctance to shut all the rads down is that following the fitting of the new boiler it literally took weeks of trial and error to get all of the rads working and I'm concerned that I may not get the main house rads up to speed again. It's a 3 storey house and during the conversion I had 2 plumbing firms at their wits end trying to balance everything up. I was hoping never to have to go through that again but it appears as if I may have to.

 

[bolshy]

You don't have to shut the lockshields, just the TRVs to stop flow to the rads. I assume you have TRVs on the original radiators?
Three storey house? Ok, now we need boiler, pump and primary heating pipe size info please. And are there any zone valves? How many rads in total?

 

[JackSkully]

You don't have to shut the lockshields, just the TRVs to stop flow to the rads. I assume you have TRVs on the original radiators?
Three storey house? Ok, now we need boiler, pump and primary heating pipe size info please. And are there any zone valves? How many rads in total?

I have been able to get good heat to 2 of the rads (the ones that were partially working before) but not the other 2.

On the 2 that are not working the pipe to the TRV gets very hot but there is nothing getting into the rad and the pipe on the other side is cold.
Any idea as to why this would be? I have removed the TRV and the pins are free.

It is a Baxi Megaflo boiler. The original rads have 10mm pipes and the new ones are 15mm. Don't think there are zone valves involved. There are 19 rads on the system.

Thanks again for your help over this.

 

[bolshy]

Where is your boiler in relation to these rads? 19 rads is a lot for a standard system boiler pump, especially over 3 floors. There will be virtually no pumping power left on the top floor if the boiler is located on the ground floor. I'm not surprised the system was difficult to balance. Your TRVs could well be jammed, try gently pulling the pins with pliers to free them, and tapping the valve body. If your system is piped up badly, and you are trying to run 4 rads on a 15mm flow/return, I'm surprised it ever worked. I don't know what size your primary flow and return pipe sizes are from the boiler, and whether they continue at the correct size throughout the system. How many of your radiators are modern low water content? Do you have a magnetic filter on the boiler return? Is your hot water cylinder flow set up correctly? Surely your heating and hot water cylinder coil have zone valves? Or a 3 port mid position valve? What controls are fitted?

If your system wasn't inhibited properly, you may have black oxide problems too, restricting flow. There are numerous things that could be contributing, but I'd start with the TRVs. And I think your pump may be struggling, it's a 15-60 afaik.

 

[JackSkully]

Where is your boiler in relation to these rads? 19 rads is a lot for a standard system boiler pump, especially over 3 floors. There will be virtually no pumping power left on the top floor if the boiler is located on the ground floor. I'm not surprised the system was difficult to balance. Your TRVs could well be jammed, try gently pulling the pins with pliers to free them, and tapping the valve body. If your system is piped up badly, and you are trying to run 4 rads on a 15mm flow/return, I'm surprised it ever worked. I don't know what size your primary flow and return pipe sizes are from the boiler, and whether they continue at the correct size throughout the system. How many of your radiators are modern low water content? Do you have a magnetic filter on the boiler return? Is your hot water cylinder flow set up correctly? Surely your heating and hot water cylinder coil have zone valves? Or a 3 port mid position valve? What controls are fitted?

If your system wasn't inhibited properly, you may have black oxide problems too, restricting flow. There are numerous things that could be contributing, but I'd start with the TRVs. And I think your pump may be struggling, it's a 15-60 afaik.

I'm afraid I don't have the knowledge to answer the technical questions in relation to heating system. As it stands I have 2 of the 4 rads now working and when I have more time I will attempt the 'close down and pull it through technique' to try and get the others running. Thanks again.