Heating not working

[Callistaraines]

One for @pigletjohn.

we have a large house with 22! Radiators. Upstairs is on one system with control panel and downstairs on another with separate control.
radiators both upstairs and downstairs have only been getting warm not hot.
we have hot water. All three systems don't seem to work when on together

heating engineer came out today and said that boiler is cutting off to stop overheating therefore radiators not getting hot.

we have a magnetic valve which he took off and emptied it was completely full of sludge.

he has recommended a flush of the pipework around the pump and possibly a new pump.

he has then suggested either a chemical flush or a power flush.

Does this sound about right??

"heating engineer came out today and said that boiler is cutting off to stop overheating therefore radiators not getting hot."

This is typical when circulation is poor or blocked.

If your ?Magnetic filter? Was full of black sludge that could be the problem

Though a lot of black sludge usually occurs when there is some other problem causing aeration of the water.

Do you have a feed and expansion tank in the loft? If so, did the gasman look at it and comment? Is it hot or flowing?

If not, do you have a pressure gauge on your boiler?

If the magnetic filter has been emptied, it can start collecting whatever other sludge is in the water. If it was me I would want to look at it after a couple of days to see what it had caught. Adding a chemical cleaner will loosing existing sludge so the filter can trap it, though it will not flow through a totally blocked pipe. The amount trapped should then decline. It is a fairly quick and easy way of getting circulation going, so very reasonable, especially as you have a filter that will trap whatever gets loosened. You can empty it yourself, ask them to show you. About as difficult as changing a hoover bag when you know how. Post a photo of it please. Like a hoover bag, it should be emptied often enough that it never gets clogged. Once a year is usually plenty. I find it very satisfying to remove a lot of sludge and have a system that runs clean. Like earwax enthusiasts.

Even after dealing with the accumulated sludge, you will have to find out what caused it.

A powerflush will cost many hundreds as you have a large system, I would hesitate to do that until the primary fault has been identified and repaired.

Many thanks piglet John.

he did go into the loft. We have a large tank up there and I believe a smaller one next to it. The only comment he made was that he'd like to come back to 'clean' the tanks?!

The problem is still occurring this evening despite the magnetic thing being cleaned out.

There will still be sludge in the pipes. A cleaning chemical will loosen it so more gets trapped in the magnet. Assuming that the pump is actually working, the cleaning process can continue for a couple of weeks while it circulates. As it continues, the amount of sludge remaining decreases, and it's noticeable that the amount being trapped by the magnet goes down. You have to remove it or it will settle again. A mild cleaner like X400 is not aggressive, even if you leave it in. It loses its power after about a month. Faster acting chemicals can be more aggressive and have to be flushed out quickly.

The tank is typically found on older boilers, which sometimes have sediment and sludge that has accumulated over many years. The design can still be used with some modern boilers, and has the advantage of simplicity.

A photo of your filter will be helpful. Is it dark red with a black cap?

Thank you piglet John, the pump is 'whirring'and we have hot water. Just the radiators that are cold apart from an upstairs towel rail which is hot and randomly the downstairs toilet radiator.
the rest of the radiators upstairs are luke warm downstairs cold

I think that's a Fernox Omega filter, I have not used them, but it is a very reputable brand. I don't know how easy it is to empty out the sludge, but I expect your installer can show you. You may find a type number on the side (e.g. TF1) and can look it up.

If you feel the large pipes, you can work out where the flow is going. The pipes that are very hot will be the flow, from the boiler, making their way to radiators or cylinder, the ones that are warm will be the Return, coming back. Any that are cold have no flow, possibly due to a blockage or to a valve that is closed, either deliberately or due to a fault. If you find a return pipe that is very hot, it suggests the water is not giving up its heat, and is bypassing whatever it should be heating.

If you have some radiators that are very hot, and some that are cold, you can experimentally turn off the hot ones and see if the cold ones heat up. If they do, it means that they are not blocked, but are out of balance.

P.s.

I am pleased to see you have luggage labels tied to some of the pipes. I expect they will be to identify what they do, e.g. "upstairs radiators flow" "cylinder return" and so on, and will be helpful in tracking down problems. Buy a Stabilo permanent marker and label anything else when you find out what it is.

An a non-urgent job, you could add pipe lagging some time, to reduce energy wastage.

P.p.s.

If the upstairs towel rail is near the hot water cylinder, it may be hot because it is heated by the cylinder supply (not the radiator circuit). This is a high quality feature, not a fault, and explains why it sometimes heats up when you were not expecting it.

Hi @ pigletjohn

so the engineer came back today. He cleaned the tank in the loft which was apparently full of sludge, he then renewed the pipes surrounding the pump area. He also put some chemicals into the system.

before he left he refilled the system and tried to start the heating. The boiler dining exactly the same thing reaching 67-68 and then switching off. Was advised to run heating continuously for a day or two to see if any improvement.
i have had the downstairs heating on since around lunchtime today and the radiators get warm but not hot.
since the hot water has been on the last hour or so they have definitely cooled to the touch.

he is now thinking it is an issue with the boiler itself. Maybe the heat exchanger and seems to think we are headed towards a new boiler. This one is only 7 years old !

we are using a well established local company but I just don't know if we ought to be getting an second opinion .

he also suggested installing a magnet filter nearer the boiler.

would very much appreciate your thoughts

@PigletJohn would really appreciate your help help if you have a spare minute

Can you identify the flow pipes and the return pipes?

The flow pipes should get hot

The return pipes should get warm.

Does that happen?

Was there more sludge in the filter today?

Are you able to go in the loft and see if the small tank is hot?

Is ANY radiator hot?

Is the tap water surprisingly hot?

Hi yes, more sludge in magnetic filter today.
the pipe where my finger is was super hot to touch but is now cool and is now back to hot.

The second pipe I'm holding is warm

Hot water is very hot but we have mixer taps so I'm not entirely sure how hot they normally are as i just turn them on in a position that I know is good for me!

This is labelled as up! Although that possibly means upstairs

I am by no means experienced at all, but could it be the pump?

I ask as I moved into my house in January. Hot water and heating was working, however we didn't realise both radiators and hot water was not as hot as it should be.
Also, radiators downstairs went cold when hot water kicked in.

Suddenly 'boiler' broke in February but when I called someone out it wasn't actually the boiler but a pump in the airing cupboard next to the hot water tank that had gone.

Once that was replaced (and a chemical flush was put in) the hot water went up by 20°C and I had to turn some radiators down!

out of the two pipes here on the left the first one is cold and the second one is warm

@ListOfJobsKeepsGrowing thank you. He doesn't think it's the pump 🤷‍♀️

Sounds like a real puzzle.
Just thought I'd share as we had no idea it was on the way out, and the first person to look at the radiators didn't pick it up.

I hope you get it fixed soon.

I can't see what those pipes do. Starting at the boiler, there will be two big pipes coming out of it for water circulation (occasionally more). One of them will get increasingly hot as soon as the boiler fires. This will be the flow pipe. The other will (should) only slowly get warm as water that has circulated round the system returns to it.

Each of these pipes will get subdivided into other pipes, there will be a flow branch to the HW cylinder, if you have one, and usually a separate flow to the upstairs and the downstairs radiators. By looking at these pipes and feeling them you can identify what they are, and if they are getting hot, or warm.

If a return pipe is very hot, then either the thing it should be heating is fully up to temperature, or the flow is bypassing it.

If there is absolutely no flow through a pipe, it will not change temperature. You can't tell where, in a blocked pipe, the blockage is, but there are ways of guessing.

P.s.

If the pump is hotter than the pipes going into it, it is seized.

If a pump is spinning, you can hear or feel it humming, and a surge when it first starts.

@PigletJohn thank you so much for all your advice so far. We ended up having new pipework to the boiler, moving the magnet filter closer to the boiler and finally a power flush. They are returning next week to balance the system.
all but one radiator is heating up. I have attached a photo. We have taken the trv off and the pin goes up and down.
interestingly it was hot when power flush ongoing but apparently this was because all other radiators were off.
the next suggestion is that either a problem with valve or that a blockage in pipe work under floor.

any suggestions would be appreciated

"interestingly it was hot when power flush ongoing but apparently this was because all other radiators were off."

That is typical of a balancing fault.

It can't be a blockage. If it was it wouldn't ever get hot.

You can turn all the others down and it will probably heat up. Balancing an entire system is a longer job, but not difficult.

If you have TRVs it might come on after the other rooms are warm. Feel the two radiator pipes and see if one of them is a bit warm.

Could that one radiator have been added after the rest of the system was installed, tapped off some other pipe? It might be a design error that will be difficult to correct.

BTW, have you been shown how to take the sludge out of the filter?

"They are returning next week to balance the system"

Oh, I see now it is already in hand.

Thanks once again @pigletjohn.the left pipe is Hot when heating is on. The one on the right is cold. The radiator pretty much is cold. Occasionally a small amount of warmth is felt in the radiator, it does get slightly warmer if only upstairs heating is on. Radiator is upstairs.

if I put my ear to the radiator it sounds like something is happening inside, it also makes faint occasional ticking noises.

hard to say if it was added to system at a later date. The house has been extended prior to us to us but the room it is in is part of the original structure.
the radiator has worked in the past and as I say was red hot during the power flush.

im reluctant to start lifting carpets and replacing pipes if it is unlikely to be that that is causing the problem.

Look at balancing on youtube.

Find the first radiator on the system and restrict the flow with the lockshield valve. Normally that is enough to help, although with 22 radiators on the system you might need to do a few more before you see an improvement.

I had a similar issue on one of my radiators and balancing the system corrected it perfectly. Took some time to get the whole system correctly balanced though and that was only with 11 radiators.