No hot water in bath when heating on?

[purpleme12]

I moved into here in the summer
Hot water always really good
A couple of weeks ago it started getting cooler in the bath I could tell. Still warm but would be too cold to stay in the bath after a while.
I think I've figured out now it's not hot when I've got the heating on!
I don't some experimenting tonight and when I turn it off again the water seems to go hot again
Can anyone shed some light on why this is happening?
I'm worried

Anyone?

This happened to my hearing once. It was fixable by heating engineer.

Heating 🤣

You say the 'hot' water is not as warm as it was without the heating on, but is still being heated - so that rules out the diverter valve. I suspect it's just a question of your boiler not being able to fully heat water for both the heating and hot water, have you tried filling the bath without fully opening the hot tap?

With the tap not on full blast you mean? Yes it doesn't seem to make a difference

@Mmmmdanone

This happened to my hearing once. It was fixable by heating engineer.

What was the problem with it? Do you remember how much it cost to fix?

Do you still have a hot water tank? We had this issue when we had a tank where a valve got sticky, we could have hot water or heating but not both!
A plumber fixed it for us, can't remember price but was less than £100 including parts and labour

I can't remember that much but it was something like diverter valve as mentioned above. Don't think it was that expensive although I think my boiler was on the way out and we changed it not long after for other reasons.

Ours used to do this. It was as simple as the boiler couldn’t cope with both heating the radiators and the hot water at the same time.

What type of boiler is it?

It's a combi boiler
No water tank

Check your pressure gauge is in green? Your boiler manual will tell you the correct pressure needed.

There’s a valve in your heating system that diverts to hot water vs heating. It’ll be stuck. Ring a heating engineer.

I have this problem. Hot water was till tepid after two hours of having both hot water and heating on. In the winter it takes forever for the water to heat up if the heating is on. It depends on the temp outside but also can be very random. I don’t know what to do. I have a hot water tank and the boiler is not a combi. Should I call a plumber?

Ours was a sticking valve but we have a tank.

Google plate heat exchanger.
This was the problem with our combi.
Gas engineer confirmed diagnosis, told me what part to buy, came back 1 week later and fitted it for me, problem solved.
Will track down his bill and tell you what he charged - though, IMHO, it's unusual to have someone advise on which part to get as, I thought, they usually supply and add a few quid on.

Have you checked the pressure level in your boiler?

Just checked his bill.
He replaced diverter valve and plate heat exchanger (£103.00 from ebay plumbing suppliers) and charged £95.00 for fitting and servicing.
West Midlands Region.

Yes I've checked pressure that seems ok
Thanks for the advice everyone
Looks like it might need a plumber then
The perils of owning a home I guess

It could be a pressure thing not enough gas coming into the house. We just got a Comby boiler and whilst we love it if someone is in the shower the gas hob the pressure goes down on it

Boiler needs servicing, it’s struggling.

Ok so I should organise a boiler service?
And mention the problem then?
This is the first time I've been responsible for a boiler so this is all new to me

It is due a boiler service I believe

Oh gosh this is going to be expensive isn't it

After having thought about this I don't think it is too do with the heating
I think it's to do with upstairs the bath and the sink.
The kitchen sink seems to get hot enough
But upstairs doesn't.
(Yet before the middle of October there was no problem with hot water upstairs)
Just tried shower and that seems to get hot enough but only if you put it right to the top heat (I don't think you had to do that previously)

Is this bad?