Unvented Tank Hot Water Supply question

[ramjet666]

I had my vented hot water tank replaced with an unvented tank recently.
The pipe work was altered and an expansion vessel fitted.

Is it normal for the hot supply to release the contained pressure after cold water has been heated and expanded?

This is more noticeable for example after a bath has been run and a large quantity of water has been re-heated.
This often leads to pressure relief noises coming from the tank cupboard of which I would think is the expansion vessel.

 

[mikeyc]

Did they fit a correctly sized expansion vessel and in the correct place? I would get a plumber who holds a current unvented qualification to have a look at it to be honest. If installed incorrectly these things can be dangerous

 

[Whn1]

I had my vented hot water tank replaced with an unvented tank recently.
The pipe work was altered and an expansion vessel fitted.

Is it normal for the hot supply to release the contained pressure after cold water has been heated and expanded?

This is more noticeable for example after a bath has been run and a large quantity of water has been re-heated.
This often leads to pressure relief noises coming from the tank cupboard of which I would think is the expansion vessel.

If what you're saying is that the water is discharging from a relief valve then no, that's no normal. And as mikes says get the original installer or another g3 qualified engineer.

 

[ramjet666]

No not saying from a relief valve. It seems like its doing what its supposed to by using the expansion vessel. Open hot tap and for a few seconds this extra pressure is released via expansion vessel. Just dont know if this is normal practise for one of these tanks or is there some sort of missing pressure limiting valve?

 

[Whn1]

I'm not understanding what you mean by releasing pressure from he vessel.

The vessel is there to handle the expansion/contraction of the water, ou shouldn't hear anything from it.

 

[mikeyc]

and definitely shouldn't be releasing any pressure

 

[lambchop]

Please phone the person who installed this, make sure he brings his ID card proving that he has got his unvented qualification. You have paid for a service and your not happy so get them back immediately. I am really reluctant to give any advice as I wouldnt want you to attempt a little bit of DIY to solve this problem, it should not be tackled by anyone who has not got the proper qualification mate imho

 

[iiplumbing]

Please phone the person who installed this, make sure he brings his ID card proving that he has got his unvented qualification. You have paid for a service and your not happy so get them back immediately. I am really reluctant to give any advice as I wouldnt want you to attempt a little bit of DIY to solve this problem, it should not be tackled by anyone who has not got the proper qualification mate imho

This is true

What kind of make on vessel is it?

Did the expansion vessel come as a package with the tank or did the installer supply that separately?

Some tanks have expansion vessels and some have an air bubble (heatrae sadia mega flow) to take the expansion

The issue may lie in how you are describing the problem, there is a difference between guessing where the noise is coming from and actually determining the source, noise has a habit of being able to travel down pipes!!

 

[ramjet666]

See photo for an idea of setup. All I want to know is it normal to see increased pressure from the hot tap after water has been heated. I dont know if this is normal or not. Then if it is not normal i can get someone in to take a look at the setup and sort it out. The original plumber is now retired.

 

[Howsie]

It's not normal.