Hot Water Cylinder Cold Feed

[hallra]

Hi Forum,

The cold feed pipework that goes into the Hot Water cylinder is very hot, I’ve never noticed this before, could someone confirm this is normal or is something wrong?

It’s hot all the way up the pipework to just below the combination valve and then a little along the pipework where it tees towards the cold water expansion vessel.


Thanks

Richard

 

[SimonG]

Get a g3 certified person to have a look at it. Non return valve could have failed, could have an issue with a mixer tap or mixer shower.

 

[SJB060685]

Get a g3 certified person to have a look at it. Non return valve could have failed, could have an issue with a mixer tap or mixer shower.

SimonG what NRV are you suggesting?

 

[SimonG]

In the combi valve.

Not the filling loop.

 

[SJB060685]

In the combi valve.

Not the filling loop.

Yes that’s what I thought lol. If filling loop was passing then system pressure would increase. I did do my G3 a long time ago so do understand this.

 

[hallra]

That’s interesting...

The combi valve was only just replaced by the plumber.

Do you believe it’s faulty?

 

[SJB060685]

I’m sure SimonG will correct me if wrong but I would of thought if the combi valve double check valve had failed then you would have heat in cold feed before it?

 

[hallra]

Ok, I’ll need to check if the heat goes passed the combi valve.

The heat definitely forks at the tee towards the expansion vessel.

- Is it ok if the heat doesn’t pass combi valve?

 

[SimonG]

Why was the combi valve changed?

 

[hallra]

I had noticed it was hissing when it shouldn’t have been, spoke to manufacturer who advised to have it changed.

I.E no taps had been opened.

 

[SimonG]

Good luck.

 

[hallra]

Simon, is that a got no idea what it is or you have some idea and it’s gonna be a pain to sort out?

 

[SimonG]

It's a pointer back to post #2.

 

[hallra]

Ok, I got you now Simon.

Interestingly, I had a mixer shower cartridge changed as well at the same time as the combi valve.

Both supplied by the same plumber.

 

[SJB060685]

SimonG can you say what exactly it is about these mixer taps or showers that can cause this problem? I don’t do plumbing work but it will handy to know in case I need to advise. I’m assuming something breaks down inside allow the hot and cold feed to blend and when the cylinder needs to refill then it draws blended cold mains back through circuit?

 

[SimonG]

SimonG can you say what exactly it is about these mixer taps or showers that can cause this problem? I don’t do plumbing work but it will handy to know in case I need to advise. I’m assuming something breaks down inside allow the hot and cold feed to blend and when the cylinder needs to refill then it draws blended cold mains back through circuit?

Got it in one. Shouldn't happen if check valves have been fitted, but how often do you see them!

Can also affect temp of hot water if it's drawing in cold.

Had a customer last year. Poor performing hot water was mentioned when I was called to a leaky shower. New shower and check valves and hey presto, hot water never been so hot in 15 years.

 

[SJB060685]

That’s the thing, I was going to say check valves would cure this but like you say you rarely see them.
Thanks buddy