weird problem - reckon only top plumber will be able to help

[dagger]

only joking with the title - any help appreciated

here is the situation

we have a bog standard old style gravity fed system with tank in loft and cylinder in airing cupboard in hall etc

Everything works fine with both hot water and radiators all year until it gets VERY cold (like now) and we leave the heating on for longer periods. This seems to have the effect of giving us just lukewarm water from the cylinder for showers etc !!!

seems weird to me as I would have thought that with the bolier going for say 5 hours rather than just 2 in the evening we would have hotter water rather than colder

Anyone have any ideas why this happens and more importantly got any tips to sort it for me

cheers

 

[oldbuffer]

There could be any number of reasons, but very likely the heating is using all the boiler's power to keep the house warm.

A central heating system has two main functions, firstly to bring the property up to the desired temperature from cold, and secondly to maintain that temperature despite the losses of heat through walls, windows and roof.

For a given structure, heat loss is proportional to the difference in temperature either side. So if its colder outside, you need to put more heat into the inside to overcome the higher losses to outside.

So when the weather is cold outside, it may be that most of your boiler's heat output is used to overcome heat losses to outside, leaving little for heating hot water.

The best solution is to insulate the property as well as possible. Beyond that you are looking at improved controls, and possibly a bigger boiler.

 

[Boilerman2]

The action of the Heating circulation pump is probably causing slight positive pressure on the Hot water Return at the boiler causing the Gravity circulation to the cylinder to slow or even stop your boiler may have an injector pipe or swept tee on the heating return which as rotted away causing this to happen.

 

[Nige F]

Turn the boiler stat up

 

[dagger]

thanks gents - much appreciated

I'll look into those options starting with the cheapest

 

[RigidRaider]

Attic insulation is the cheapest.