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new boiler installed, heating fine, hot water cylinder takes ages to heat up although flow and return from cylinder are piping hot, and boiler is going out on temperature, motorised valve and cylinder stat ok, you can get hot water from the immersion heater, but not from the boiler, there is no air lock, as aav,s are working. Any ideas.
Geoff

Was it only the boiler that was changed? If so was there any valves between the boiler and the cylinder closed off that may not have been fully reopened? Are the AAV's fully working? The AAV's have small orifaces which can be clogged by debris from the work carried out, could be worth making sure they are clear and working ok.

[quote="The Heating Doctor"]Was it only the boiler that was changed? If so was there any valves between the boiler and the cylinder closed off that may not have been fully reopened? Are the AAV's fully working? The AAV's have small orifaces which can be clogged by debris from the work carried out, could be worth making sure they are clear and working ok.[/quote]

no valves in between, aav's ok, boiler exchanged was an old wall mounted ideal boiler about 20 years old, flow and return from cylinder to boiler approx 3metres, return going into common return just before entering boiler, i suspect the coil externally could be scaled, as i have now been told the previous boiler took just as long.

I suspect you are right, but just a couple more questions before you go down the expensive route of changing a cylinder cica £120-170 + vat.

1) Do you have 22mm or 28mm pipe work from boiler to cylinder?

2) Is the water pumped or gravity fed to the cylinder?

[quote="The Heating Doctor"]I suspect you are right, but just a couple more questions before you go down the expensive route of changing a cylinder cica £120-170 + vat.

1) Do you have 22mm or 28mm pipe work from boiler to cylinder?

2) Is the water pumped or gravity fed to the cylinder?[/quote]

both 22mm as previously installed, pumped hw and htg, cylinder about 15 years old, in a hard water area.

as i suspected, cylinder coil very scaled up, new cylinder to install
geoff lee

As you have to install a new cylinder for around a further £40, install a lime descaller on the cold water inlet to the house. Available units are Liff lime fighter, Calcombi inhibitor, Scalemaster or Combimate. These will help reduce the amount of lime to boiler & cylinder.