Worcester 42cdi Hot water problem

[pianogeezer]

Hello,
I have a problem with my Worcester Greenstar 42cdi. It was working fine until yesterday. when I noticed that the hot water would not get hot. upon further investigation, I am even more baffled.
The boiler is in the upstairs bathroom.
1. Bathroom sink, (closest to boiler) gives warm water.
2. Bath tap, warm but not hot enough for a bath.

If I run both taps at the same time, the bath tap goes cold, but the sink tap gets boiling hot. I cannot get the bath tap to give out hot water. Also, hot tap on kitchen sink wont only giving cold water. I have isolated shower and mixer tap, but problem persists.

Any help greatly appreciated as wife is frustrated!

 

[Chuck]

Do you have a shower that mixes hot and cold water? If so, I suspect it's not isolating the hot and cold supplies properly and is allowing cold to feed into the hot pipework. Relatively easy to confirm by feeling the temperature of the pipes and applying a bit of logic.

 

[pianogeezer]

Thanks for the quick reply. Ive isolated the shower hot and cold, but still have the same problem.
[automerge]1567000353[/automerge]
Am I missing something?..... having isolated the shower and mixer taps, I believe this problem is theoretically impossible i.e. When I turn on the hot taps on the Bathroom and Kitchen sink, the bathroom sink tap is giving hot water and the kitchen sink tap is giving cold water (not even warm)! Is there a scenario where this is possible?

 

[centralheatking]

Is this a new installation or an old friend gone wrong ?
chking

 

[pianogeezer]

Is this a new installation or an old friend gone wrong ?
chking

it was installed about 5years ago, its been running great, no problems at all.
[automerge]1567007707[/automerge]
Ive found the problem!...
the garden hosepipe is linked to the hot water system, It was fitted a few years ago but never been used. It is connected under the kitchen sink, (hot and cold merge into the one pipe which goes outside to the hosepipe).

I switched the hot on to fill the swimming pool for the grand daughter and forgot to switch it off afterwards. Obviously, it is not a one way valve as when this valve is open, the cold water is running into the hot water pipe.
What type of valve should this be?

Thanks for your help

 

[centralheatking]

it was installed about 5years ago, its been running great, no problems at all.
[automerge]1567007707[/automerge]
Ive found the problem!.
the garden hosepipe is linked to the hot water system, It was fitted a few years ago but never been used. It is connected under the kitchen sink, (hot and cold merge into the one pipe which goes outside to the hosepipe).

I switched the hot on to fill the swimming pool for the grand daughter and forgot to switch it off afterwards. Obviously, it is not a one way valve as when this valve is open, the cold water is running into the hot water pipe.
What type of valve should this be?

Thanks for your help

That really is a one off for UKPF never seen one like this
centralheatking

 

[pianogeezer]

That really is a one off for UKPF never seen one like this
centralheatking

Yes, your right!
Hot and cold water pipes have lever ball valves fitted then go to ONE copper pipe. cold is always on, when I switched the hot on, and the hosepipe was off, seems like the cold water was making its way into the hot water feed.
What type of valve needs to be fitted to prevent this?

 

[ShaunCorbs]

Double check valve

But tbh you shouldn’t have them connected also there’s a backflow risk with the pool

 

[pianogeezer]

Many thanks to all who replied.

 

[centralheatking]

Double check valve

But tbh you shouldn’t have them connected also there’s a backflow risk with the pool

A potential risk, double check valve yes £7.00 from Bes Electric Ave Brum but unless your pool is higher than the lowest cold water point in your home which is rare then the risk is minimal in real terms.
Wras regulations are a world standard to which many countries
subscribe they cover all installations, fitters and devices in contact with the drinking water supply right down to induvidual homes and quite rightly so.....centralheatking if you get it wrong you might be having pool water in your expresso or your kids sorbet but its unlikely

 

[EvilDrPorkChop]

Outside tap might have a non return valve in, preventing back flow from the pool. The Hot and Cold is tee'd together before the tap. You need a non return valve after the hot isolator as others have said.

 

[king of pipes]

This is not the way to do it for all sorts of reasons one of which you have now identified , employ a plumber to separate the supplies and fit the equipment to have a warm water supply externally. Kop