Heating cools down when hot water on?

callmechar

Boiler is a Worcester Bosch 18ri. Newly installed in June. It's not a combi. When both the hot water and heating are on the heating doesn't really get hot. Turn hot water off and it heats up. A new bypass valve was fitted a few months back.

macman

I suggest you get back the installer who fitted the motor valve. Is the boiler output sufficient for the demand of the property?

Bogtrotter

What system did you have before the new boiler was installed?

I have a dual solid/oil heating system and get the same issue.

I think it's because the heat exchanger coil has no balancing valve so when you switch on heat and water most of the hot water from the boiler takes the path of least resistance though the hot water cylinder. Since I wish to retain the solid fuel heating capability I can't fit a balancing valve on the cylinder.

If gas is your only fuel you could get a plumber to fit a balancing valve on the hot cylinder and balance the hot water and heating system. If you do this however you will find that the time taken to produce hot water will be much longer since you are restricting the boiler flow through the cylinder coil.

If you need constant hot water/heat it may work for you but if you are able to predict your hot water requirements the best thing would be just to plan your system operation. For example in the morning have the heating coming on before your hot water to get the radiators up to temperature before producing hot water.

southcoastrgi

turn the auto bypass right down

callmechar

Husband fitted the three way valve. This valve was replaced before the boiler. On the last boiler the heating wouldn't come on unless the hot water was on. It did this before and after new valve fitted.

Boilers aren't meant to work like this are they?

southcoastrgi

callmechar wrote: »

Husband fitted the three way valve. This valve was replaced before the boiler. On the last boiler the heating wouldn't come on unless the hot water was on. It did this before and after new valve fitted.

Boilers aren't meant to work like this are they?

no they aren't one of two things either programmer is old & will only let it work as you describe but more likely the mid postion valve is wired wrong, if your OH wired it back the same way as it was then this is prob the problem

Canucklehead

Hi.

You need to call the installer back.;)

I had a new boiler installed today. They are coming back to finish tomorrow. Husband done central heating himself. So only the boiler being done.

Time to get the camera out again, lets see what he did in the cylinder cupboard.

GSR.

callmechar

Sorry for late replies

My husband says that he has wired the 3 way valve in correctly (said there is not auto bypass valve). Any other ideas please?

keystone

I don't believe him . He HAS done something wrong somewhere. For pities sake tell him to grow a pair and recognise his limitations. Theres a big clue in post #5 that all is not well and an even bigger clue that you know it!!

Get the installer in who fitted your boiler to check it all out. If you don't this thread will still be running in the summer.

Oh and as asked by CH. How about some pics to see what things are like around the cylinder.

Cheers

callmechar

Ok will post photos but in meantime husband said problem with the last boiler was the motorised valve was not stuck in manual position. He replaced this. He thinks there may still be air in the system - could it cause this? He is bleeding it as we speak

keystone

callmechar wrote: »

Ok will post photos but in meantime husband said problem with the last boiler was the motorised valve was not stuck in manual position. He replaced this. He thinks there may still be air in the system - could it cause this? He is bleeding it as we speak

The motorised valve is NOT supposed to be stuck in the manual position!

Arrrrgh! Stop listening to him. There was a problem before and he couldn't/didn't fix it. There is a problem now, He still hasn't been able to fix it. There is a reason for that and

Boilers aren't meant to work like this are they?

says that you know it only too well.

Perhaps he should be bleeding as we speak.

Cheers