Radiator not getting hot

[JohnD]

if you turn off all the hot radiators, does the cold one then warm up?

if so, it is most likely because there is an easy passage of flow through the hot one(s).

If there is an easy path, them the hot water will tend all to go through there, especially if it is closest to the pump, it will circulate through the path of least resistance........

etc

etc

if all the hot water is flowing through the easiest rad, there will be none left to go through the others.

Come back when you have closed all the lockshields and opened them not more than half a turn. From that point, only adjust any lockshield by a quarter turn at a time. close the hottest ones down and feel all the return pipes to see if they are about the same temp. if not turn down the hottest one a shade, wait ten minutes, and feel again

if you read the earlier posts on here, you will see this has been mentioned before.

 

[merton69]

The 3 upstairs rads are off and cold. The double rad (original problem rad) gets hot but not as hot as the rad that doesn't have a TRV. These two downstairs rads are last in the flow.

What I am querying what nobody seems to be able to answer is that 'you' are asking me to turn the LS now after 10 years of not being touched? In other words, the flow and heat have been fine for 10 years with the LS's being as good as fully open on all of the rads, so why should we be questioning the LS's position all of a sudden?

Surely, the problem lies with something else?

Can the pump give a reduced flow because of gunk managing to get inside?

 

[JohnD]

What I am querying what nobody seems to be able to answer is that 'you' are asking me to turn the LS now after 10 years of not being touched?

Yes, we're asking you to do the one thing that will help

Surely, the problem lies with something else?

If you're not willing to do the one thing that will help, I'm out.

After you've done the one thing that will help, you can talk about anything else you want.

 

[merton69]

JohnD, i really do appreciate your help but can I ask again what are the reasons for doing the LS process please?...that's all I ask....what will it determine please?

 

[merton69]

I have flushed the system right through and flushed each rad individually.

I have done the LS process and the rads do get warm but takes ages to do so.

 

[JohnD]

I have done the LS process and the rads do get warm

hooray

All of them equally hot and equally fast?

 

[merton69]

As good as but some takes ages to get to temp.

The whole system takes a long time to get to temp. It wasn't like this before the initial problem of the downstairs rad staying cold, the rads got to temp at the same time and quickly without having the LS set at what they are now.

 

[JohnD]

start by opening the LS valves by a quarter turn more each, starting with whichever one is coolest. Keep a note of how many turns so you can reset if necessary. Check what speed the pump is set to.

Have you used a sediment-removing chemical cleaner such as Sentinel X400 yet?

you can take the pump off if you like, see if the ports are choked with sediment or the impeller corroded. You close the pump valves to stop water gushing out. If you momentarily connect the pump, you should not be able to stop it with your finger.

...It is also possible that your system has a bypass pipe fitted to allow circulation even if all the rads are turned off, as might happen if you have TRVs on all rads and no room stat. In this case you will find the flow and return pipes at the boiler are both very hot, and all the rads are cold, so you have to follow the pipes until you find the bypass connecting hot and cold. It may have an adjusting valve on it but should never be fully closed...

did you look for a bypass, and have you got one?

 

[merton69]

I have some cleaner fluid but yet to put it in, just in case I needed to flush the system again.

When the system is running properly, I will add it.

My next job is to check the pump as this is what I have always felt was the problem, right from the beginning.

I will return on inspection of the pump!

I would just like to take time out to thank you all for assisting me with hopefully sorting the problem out and saving me a fair bit of money!!

 

[JohnD]

which chemical have you got?

 

[BARNY78BG]

hi mate. i'm new on here and have read your posting, just thought i'd mention what no one has said,, if you've not altered your boiler or system in any way at all since installation and are now getting circulation issues, then clearly it's either your pump is wearing down and is not as powerful as it was, then change pump, or your system is producing magnetite(sludge) and is slowly but gradually restricting your system and boiler.
taking rads off and flushing through with a hose in the garden is a temp fix at most!!!!! what no one has explained is that when magnatite(sludge) is produced in systems its not just the loose stuff that poses restrictions but it actually solidifies and coats pipes,valves and passagways(just like arteries blocking)causing flow or return issues.
therefore, the only way to get your system running well again is to powerflush it. also by washing through your rads as your doing, you are adding fresh water and that is adding to your troubles of corrosion.
As to your trv's, the pins can appear to move even when stuck cos they might be stuck on seat of valve body and pin may move only and, as the guys on here have mentioned they need a few taps, honestly not trying to step on toes of other engineers, but thought my input would help????

 

[merton69]

Thank you Barny!

Your answer is what I have been asking for sometime now and nobody (until now) has suggested this.

I have always thought it may be the pump which is why I was asking why do the LS process, as I thought this would not alter the pumps own output.

Surely you only alter the LS if a rad is being added or taken away.

 

[BARNY78BG]

systems should be balanced when installed and should only really require re ballancingif system loads change

 

[merton69]

Can the pump be disconnected and inspected by me or does it need a Corgi registered engineer to do this as it means that the covers to the boilers need removing please?

Also does the electric feed to the boiler need to be switched off please?

Does the boiler need draining as well please?

View media item 40827

 

[merton69]

....the story continues.........

I have just emptied the boiler and removed the pump for inspection and a clean.

All appears to be fully working okay!.....

..and still the system is not working properly. The double rad still takes ages to warm, which perhaps suggests that an air lock is in the CH somewhere!?

The air lock in the system, I believe, has decided to lodge itself in the downstairs double rad, which is why is struggles to warm.

I am thinking of adding a drain off cock to the double rad hopefully getting rid of the air lock because the the drain off cock is on the other and downstairs single rad, which won't get rid of an air lock anywhere else.

Is this a good course of action please?

Or any suggestions will be very gratefully received!!!

View media item 41006