Boiler & Hot Water problem

mark46327

I've recently had an open vented central heating + hot water sytem installed. So far, it has just been used for hot water. However, I've noticed that despite the cylinder thermostat being set to 60 degrees the hot water only gets to 40 degrees (measured with a thermomoter) despite the system being on for 3 hours. The boiler temperature is set at 70 degrees.

Turning the cylinder thermostat up to 70 degrees makes no difference.

Turning the boiler temperature up to 82 degrees does make a difference however. The hot water reaches 58 degreees (with the cylinder thermostat set to 80 degrees) after three hours, but with the cylinder thermostat still at 70 degrees I'd expect more!

So, it seems to me the cylinder thermostat is working OK, it it just taking a long long long time to heat the hot water.

I have noticed something odd with the boiler (a gloworm 24hxi) however. If the boiler temperature is set to 82 degrees, for example, the boiler turns on (surprisingly noisily - sounds like a steam train!) and heats for about 10 seconds until the boiler water temperature is shown around 82 degrees. Then the boiler turns off. The boiler temperature then drifts down to about 58 degrees before turning on again for 10 seconds or so until the temperature is back around 82 degrees.

So, my uninformed conclusion is that the boiler is doing strange things and so is very slow in heating the hot water. I would expect the boiler to keep the boiler water temperature at about 82 degrees until the hot water is up to temperature. Am I right or is what the boiler is doing perfectly normal?



Thanks,

Mark.

Canucklehead

Hi

It sounds to as though the system is not being pumped around quick enough, the boiler is reaching temperature too quickly.You might have a valve on the cylinder return that's not open enough , a partly blocked 2 or 3 port valve or the pump is blocked or failing. You could check that your expansion tank in the roof is full. Your Corgi should be able to pin it down easily enough.

Corgi Guy.

mark46327

OK, thanks. The expansion tank is full, so that's OK. I'll get the original Corgi installer to investigate.

Out of interest, there is a heated towel rail on the hot water circuit. Is this normally plumbed in as part of the circuit between the boiler and the cyclinder or in parallel - i.e. is it OK to turn the heated towel rail off and not affect the hot water?

Mark.

Canucklehead

Hi

A good system will have the towel rail on the hot water circuit so you can have warm towels all year.(useful this year!) I would ask your Corgi about turning it off as he/she might just have used it as a bypass.
Corgi Guy.