3 rads heating up with hot water

[TryingHardDIY]

We have recently moved into house with very old CH system. I have chemically cleaned the system and all rads are heating up nicely. However with summer approaching we don’t need the heating as much. I have noticed that when the hot water comes on for 40 minutes in the morning and 40 minutes in the evening there are certain rads heating up! I have eliminated the motorised valve being an issue as the pipe that feeds the rads after the valve is cold and the hot water feed after the valve is HOT...cant even touch it...which is as expected.

When I switch the heating on it works fine it is only when the hot water is on that their are a few rads that get fully heated. On a separated note there are also some rads that get mildly warm, no more than luke warm, is this normal and as a result of hot water running through the pipes?

Some backgournd information that may assist regarding the rads heating up with the hot water;
All three are near the boiler. The boiler is in the kitchen which is an extension to the original build. The room above the kitchen is also an extension and this use to be the bathroom. The rads in the kitchen, upstairs room (above the kitchen which also has the airing cupboard with hot water tank,etc.) and hallway (which use to be old bathroom) are the one heating when the hot water is on. As I say some other rads do also get a bit warm but nothing of concern.

Any idea why these 3 rads keep getting hot with the hot water?

Any ideas will be much appreciated.

Thanks

 

[ALCPlumbing]

Most likely due to how the pipes have been run. There is thread on here somewhere with a picture explaining your problem. If I can find it I will post the link.

 

[TryingHardDIY]

Most likely due to how the pipes have been run. There is thread on here somewhere with a picture explaining your problem. If I can find it I will post the link.

That would be great. Thanks. Doubt it will be covered by my CH insurance to fix?

 

[Armo74]

It is usually normal for at least 1 rad to get hot whilst hot water only is on this is usually a bypass rad.
It sounds like the others have probably been piped into the main primary's from the boiler instead of the heating circuit.
The pipe configuration in your airing cupboard also wants checking as the hot water return maybe piped up wrong.

 

[TryingHardDIY]

It is usually normal for at least 1 rad to get hot whilst hot water only is on this is usually a bypass rad.
It sounds like the others have probably been piped into the main primary's from the boiler instead of the heating circuit.
The pipe configuration in your airing cupboard also wants checking as the hot water return maybe piped up wrong.

Thanks Armo. Am i correct to think it does no harm other than make it uncomfortably hot in the summer? I.e. no damage to the system?

 

[adamsheating]

Do the pipes on the radiators get hot In The same direction in both cases?

Sometimes depending on how the system was piped you could could get back flow on some of the radiators. It could be sorted out by an appropriately fitted NRV.

 

[Armo74]

Not particularly harmful but uncomfortable and wasteful in terms of energy.

 

[TryingHardDIY]

Do the pipes on the radiators get hot In The same direction in both cases?

Sometimes depending on how the system was piped you could could get back flow on some of the radiators. It could be sorted out by an appropriately fitted NRV.

3 of the radiators get fully warm as if the heating is on, all the others in close vicinity of these three get slightly luke warm, mainly at the inlet pipes. As long as it is not doing any damage to the system im not that worried as i can just turn the rads off at the valves for the summer i guess.

 

[TryingHardDIY]

Not particularly harmful but uncomfortable and wasteful in terms of energy.

mmm...i think i will most probably leave it for the moment. We want to get a combi eventually so will do it then i think. Thanks again.

 

[Armo74]

Did you sort the other problem with the radiator that wouldn't heat up after the chemical clean?

 

[TryingHardDIY]

Did you sort the other problem with the radiator that wouldn't heat up after the chemical clean?

Ha ha...yes. Thanks for asking. It turns out there was a huge amount of air in the downstairs rads which i didn't bleed properly or in the correct order. I then bleed them and shut off all valves except the affected rad...it was piping hot within minutes...Result!!

The CH system is doing my head in...i have now drained the system again to clean out the X800. Need to drain once more for X100 to go in. Its been every weekend for the past 3 weeks!!!

Anyway, i took your advice on bleeding this time round and it seems to be working a dream.

One issue that did start yesterday was the cold water storage tank is making a racket when it refills. Can this be sorted with a new part 2 ball valve?

And one last question since i have you in my grips...Should the pump on the CH system be 1/2/3? The engineer that fitted it 2 weeks ago left it on 3? I read that this may be too high?

Thanks for all your help Armo, you cannot begin to understand the stress you save me!

 

[Armo74]

How many rads do you have?
Speed setting 2 is usually sufficient.
Set it to 2 make sure that the rads heat up ok and see if it makes a difference to the noise.

 

[Armo74]

Is it the feed and expansion tank that's making a noise on re-fill or the cold water tank for the hot water?

 

[TryingHardDIY]

How many rads do you have?
Speed setting 2 is usually sufficient.
Set it to 2 make sure that the rads heat up ok and see if it makes a difference to the noise.

11 rads. Will give it a go on setting 2 then.

Apologies, the noise on the pump is fine. Its a seperate issue... I was referring to the noise from the loft when the CWST fills after a bath/shower. I think a new part 2 ball cock might sort it out?

 

[TryingHardDIY]

Is it the feed and expansion tank that's making a noise on re-fill or the cold water tank for the hot water?

Apologies, Cold water tank. it currently has a very old part 1 ball valve...i think.