Cleanser

[awmech]

I have had my system power flushed as I was advised by BG engineer, which hasn’t solved the problem I’m having.
The issue is cold radiators downstairs, the boiler keeps stopping due to over heating apparently, so it spends more time off than it does on.
Typically only runs for about a minute or two at a time.
I’m getting a “reasonable” amount of heat to the upstairs radiators but nothing like before summer, when all seemed ok.
The pump was replaced also, as I believe that could cause lack of heating downstairs, but don’t think that was the issue.
The hot water heats up but takes a long time to do so.
This is a gravity fed system with tanks in the loft, hot water cylinder etc. and a Potterton Suprima 40 boiler (about 27 years old) but no vent.
During the power flush some heat was getting to downstairs rads, so have also been recommended to go with a combi boiler as it will move water around better.
It’s 10mm pipe work to all the rads.
Meantime, he suggested dropping in a cleanser and leaving it in for a few weeks while I’m away working, then flush through for a few hours.
Only thing is he suggested Sentinel 800 which I believe shouldn’t be left in for that long?
Anything I can use to leave it in a few weeks?
Anything I can try in case of an air lock?
TIA

 

[Madrab]

so have also been recommended to go with a combi boiler as it will move water around better.

Absolute garbage!! Jeesh, I'll tell you, some of these guys should be feckin shot for saying really stupid things like that!!

X400 can be run in the system for weeks.

If you turn off all the upstairs rads can you get heat to the downstairs ones?

the boiler keeps stopping due to over heating apparently

If this is the case then it's probably a circulation issue and therefore ........

It’s 10mm pipe work to all the rads.

Guaranteed that'll be one of the primary issues if it's been in for a long time on an open vent that hasn't been looked after, as that will undoubtedly be restricted - you say it doesn't have a vent, presume its a combined then, so in essence you do it's just not an open vent that's up and over the F&E cistern.

How is the system piped? Does it have a 22mm backbone and does that run to downstairs or is it all pretty long 10mm runs?

 

[awmech]

Thanks for the reply, the engineer said the combi boiler would be pumping water round at a higher pressure than the current pump which would help, we were seeing some heat in the downstairs rads whilst the power flushing was ongoing, which I was told was pumping around the same pressure as a combi boiler.
It’s 22mm pipe from the boiler up to the pump and zone v/v, after that it’s 22mm but disappears, so I can’t say where it drops down to 10mm.
I’ll try shutting upstairs rads as haven’t tried that since the power flush was done a couple of days ago.
The house is almost 28 years old, all the pipe work, rads and boiler are original.
Only things that have been replaced are a couple of PCBs, the pump and the zone v/v.
When I say no vent you are right, there isn’t one up in the loft but there is an AAV on the hot water coil at the cylinder.

 

[awmech]

Another thing I thought was maybe the heat exchanger in the boiler is choked?