Cold radiator since new boiler fitted

[copernicium]

Had a combi boiler installed two weeks ago. All radiators worked when they left but one downstairs stopped heating at all a few days later. They came back, drained the system again and it was working. Now it's stopped working again.

Is it acceptable to call them back again, or is this not their problem? Is there anything I can do to fix it? I've tried bleeding it, checked the TRV and made sure the valves are open.

Def call them back. Something isn’t right & they need to sort it for you.

cold all over, or cold in parts?

cold all the time, or some of the time?

turn off ALL the hot ones. Does it now heat up?

I'd get them back as many times as it took to get the whole system working properly again.

It's cold all over. The pipes coming to it are hot. They've said they've just disturbed the sludge in the system and I need a new radiator - but wouldn't that make it hot in parts?

Should I turn off all the hot ones when they are hot or cold? And is there an order to turn things back on?

It was fine before, it was fine for a few days after the replaced the boiler and it was fine for a few days after they came back.

Glad to know gas engineers expect to be called back!

both the pipes are hot? Or just one? is the bottom rail hot?

yes, turn off ALL the others. By their knobs. Doesn't matter what order.

Just one and the bottom one.

But interesting comments about the sludge. I'll be calling them back in the morning!

@PigletJohn they came and replaced a valve and it worked ... until last night 😡. I've just tried your technique, all the radiators are off and the kitchen one is working. Is that is now, should I turn the others back on or? (Thank you for being a genius!)

They need balancing.

Out of my 52 previous posts on Radiator balancing, this one looks quite comprehensive:

www.mumsnet.com/Talk/property/a2205419-New-radiators-not-getting-hot#50023831

Thank you!

@PigletJohn you're a hero! It's taken a while but I now have 8 hot radiators. Thank you 😊

that's good.

I was a bit concerned by the mention of sludge. Do you know if they powerflushed the system and/or fitted a magnetic filter?

did you have a combi before, or an old iron boiler?

when you bleed a radiator, what colour is the water?

They fitted a filter, they said a power flush would be an extra £700...but now all the radiators are working, surely there's no sludge?
I had the oldest boiler & tank you've ever seen before, and when I bleed it it's clear...

did they show you how to empty the dirt out of a filter?

a photo may be useful.

They didn't even mention it needing emptying...

I haven't used Salus Defender but it looks like a budget copy of a Magnaclean.

Best to ask the installer, or the next person who services the boiler, to empty it and show you how it's done. Quite often a lot of old sediment is disturbed during CH draining and changing a boiler.

The instructions should be on
salus-controls.com/uk/product/md22a-md22awo/#downloads