Replaced two Radiators, been told we now need to replace pipes feeding radiators…

[IanM18]

Looking for advice.

Had two radiators replaced. It’s worth mentioning that the previous rads were about 15 years old, but worked and heated perfectly. We were getting work done, had to get them removed so thought while they were off, put new ones on.

New radiators installed, and they both get hot at the top, warm (ish) at the bottom.

Pipe in, is red hot to touch, pipe out is barely warm.

Have been playing around, switching off other rads.

If everything else is off, one of the new rads gets normal hot, pipe in and out red hot. The other one, stays hot at top, warm at bottom.

Switch off one of the new rads, and the other doesn’t change, warm at top, cold at bottom.

Plumber came out to check, thinks the pipes feeding the rads all need changing, something to do with pipes feeding diameters, and number of radiators off each, to be honest, was all a bit confusing.

I don’t mind getting additional work done if it’s needed, but just looking for opinions.

Old rads worked fine, new ones don’t (same size as old ones).

How can that go from working fine, to needing new pipes from boiler?

He says it’s all balanced as well.

Is there anything I could be missing, or is it likely that we need to get the other pipes replaced as well?

Cheers!

 

[Madrab]

Did the size, type of the radiators change? What size is the pipe entering and leaving the rads?

 

[IanM18]

Rads same size, different make though. Pipes into rads, the normal 15mm copper pipe.

Suggestion from plumber is, that there are too many radiators on a 15mm circuit, and that needs reducing, by adding extra 20mm in, then running 15 off to the new radiators (or something like that) was difficult to follow really

What I can’t work out, is it worked before, now it doesn’t, so pipes must have been able to support the flow?

If the pipe going “in” is red hot, but the pipe out is lukewarm.

Does that suggest anything?

Thanks for any help by the way, appreciate it

 

[Mister Banks]

A hot input with a lukewarm output suggests the radiator is working.

 

[IanM18]

A hot input with a lukewarm output suggests the radiator is working.

Thank you, that’s good to know. Is there any reason the bottom of the rad would be also lukewarm?

 

[Koolpc]

Doesnt make sense if only thing changed is new rads. Maybe that rad / valve is faulty?

 

[Koolpc]

Thank you, that’s good to know. Is there any reason the bottom of the rad would be also lukewarm?

Balancing i would have thought....but...

 

[terryplumb]

Are the new rads conventional panel radiators ? Where old rads single panel and new rads double panel ?
If the rads are actually like for like replacements there is no reason why they shouldn't work with existing pipework.
Have any additional rads been added to the system anywhere ,where there wasn't a radiator before ?

 

[IanM18]

Old rads were also double panel, only new radiator we added was installed on upstairs zone, these ones are on the downstairs zone.

I’m going to have a go myself at balancing the system, worth a try before spending another grand on new pipe work I guess!

 

[spile]

Definitely worth experimenting with balancing. If you have a problematic rad, turn the lock shields down on every other rad to confirm it’s working and there isn’t a pipe issue or blockage. The gradually open the valves on each rad in turn just enough for them to heat up whilst maintaining a good temperature difference between inlet and outlet.

 

[IanM18]

Totally, the wifey thinks it’s a good idea as well before I spend another fortune

 

[Stuart981]

You could try taking the radiators back off. Stick buckets under the wheelheads and lockshields and crack them open one at a time to check check for a goodly flow.

 

[IanM18]

Weird question time

Been checking temps over existing radiators, and on one of them, one pipe with the lockshield on is 60, the other side with the TRV on is 30, shouldn’t the TRV be on the “in” side?

Could this be causing some problems?

 

[foxhole]

Could be a sludge blocking valves, was system flushed?

 

[terryplumb]

Weird question time

Been checking temps over existing radiators, and on one of them, one pipe with the lockshield on is 60, the other side with the TRV on is 30, shouldn’t the TRV be on the “in” side?

Could this be causing some problems?

Most TRV's are bi directional and can be fitted on flow or return sides without issue .