Glow Worm 30cxi slow to heat radiators

14 Jun 2005
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United Kingdom

Firstly, I am writing this on behalf of my parents, so forgive me if I don't have all the information. They live in a large semi-detached four bedroomed victorian house.

They recently had their old bolier (standard boiler with hot water storage tank) replaced with a Glow Worm 30cxi to provide heating and instant hotwater.

My mum now complains that though the hot water is instant, it takes ages for the radiators to get warm (around half an hour), where as with their previous boiler it was almost instant. They have TRVs fitted upstairs, but non down.

The boiler is controller by a Glow Worm Climapro RF programable stat.

When you switch the heating on via the stat, the boiler kicks into action because you can see the steam coming from the flu, it just takes ages to get the radiators up to temp.

Is this normal (some kind of slow heat up to save energy) or is something wrong? They had the installer back who seems to think everything is ok.
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Even though the boiler isn't big for the type of house, I'd expect the radiators to be pretty hot within 15 minutes or so.

When first switched on using the room thermostat and the radiators are still cool, does the boiler sound as if it's running flat out the whole time?

I suspect it is starting to "throttle back" soon after starting up, while the majority of radiators are still nowhere near hot.

Do any of the radiators get hot long before the rest?
Apparently the upstairs radiators get hotter quicker than the downstairs one, but not by any major amount of time.

I will get my dad to sit next to the boiler for half an hour the next time he turns it on and report back!
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Finally fixed. Thought I would post the solution in case anyone else comes accross it.

The Glow worm engineer had been out three times last year tinkering with vaious things (including replacing radiator valves) but nothing worked.

Then just before Christmas, he came along, tinkered for a couple of minutes with the Glow Worm Climapro RF programable stat and everything was fine.

Turns out they "hadn't been trained properly" on these, and on a default install the stat is programmed to heat the hotwater tank and only then do the central heating.

Well, my parents don't have a hot water tank, so the signal to turn the heating on was coming in at a random time!

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