Shut off valve for hot water

[LCV]

Hi,

I've had a new heating system installed (system boiler and indirect unvented pressurised hot water cylinder) as part of a house renovation. I've had two plumbers in, plumber1 who is part of the loft conversion company and the plumber2 part of builder's team for the rest of the house.

When plumber1 was connecting loft to the heating system he said that he noticed there was no shut off valve for the hot water. As one was not there he said he had to wait 45mins for the hot water to drain and if I had a shut off valve then he wasn't have had to do that. As such he would recommend asking plumber2 to put one in above the hot water cylinder.

However when I approached plumber2 with this request he said it was illegal to add a shut off valve above the hot water cylinder and if he did so there is a rest it would explode as it is a pressurised system.

I am very confused as plumber1 seemed to be a very competent plumber so I doubt he would have advised doing something so dangerous. I wonder if plumber2 is just saying that because he doesn't want the hassle of adding it in or perhaps I have misunderstood what plumber1 was advising me to do.

Great to hear your thoughts on this.

 

[Jay The Plumber]

Im pretty confused by your post..

what does the hot water cylinder have to do with heating system ?
the way I read the post was that plumber 1 drained the domestic hot water to install heating in the loft ?

 

[PlumbBobBob]

it is usual to have an isolator, either gate valve or lever ball valve on the cold feed to the cylinder but not usually on the hot leaving the cylinder. is your cylinder open vented or unvented?

 

[Jay The Plumber]

he said the cylinder was unvented so yea, valve on cold feed.
its the "draining the hot water installing heating into a loft conversion" which is worrying.
hoping that OP has misunderstood both plumbers

 

[Riley]

Having a valve on the hot and cold pipework is no different to having a tap at an outlet???

 

[kris]

Pressurised system takes seconds to drain as, when you switch mains off your only draining wots in the pipe work, are you sure you haven't picked him up wrong, is he not on about draining your old tank to fit the new one??? Either way isolation valves are preferred on most pipe work situations,

 

[Rickster123]

Which of the two plumbers is g3 qualified? I'd be taking his advice only.

 

[Riley]

Which of the two plumbers is g3 qualified? I'd be taking his advice only.

Ooh the testing question

 

[chris watkins]

Not withstanding the above post.
It is possible to have a valve installed on the hot water outlet (normally out of the top of the cylinder) so long as all the safety valves & any expansion vessel connections are not interrupted.

It is not usual on most domestic systems as the hot water isolation is normally carried out by turning off the valve on the cold feed as others have said.
If you have a balanced cold water supply feeding the rest of the house & separate isolation of the hot & cold systems is required, then the isolation of just the hot can only be achieved by the insertion of a valve on the hot outlet.

 

[LCV]

Thank you very much for your replies.

Plumber1 had recommended putting in a full bore 22mm lever valve to shut off the hot water supply coming out of the unvented pressurised hot water cylinder.

Plumber1 was on site to do second fix in the loft ensuite and the radiators in the bedrooms. He said he turned off the cold water and when he went to look for the shut off valve for the hot water he couldn't find it. He said is it normal to have both. This caused him to have to wait 45mins for the water to drain.

He said if I ever had a problem and called out a plumber they would have to wait 45mins too and I would be paying for them to stand around which I obviously don't want to happen. But if I had a shut off valve above the hot water cylinder then it would be a simple case of turn off, cold and turn off hot and job done.

 

[LCV]

From reading your replies, it sounds like it is not standard to have a shut off valve above the hot water cylinder. Is it just not needed or not advisable to have one (because it is unsafe, illegal as the builder said).

I wonder why plumber1 said what he said?

 

[Jay The Plumber]

From reading your replies, it sounds like it is not standard to have a shut off valve above the hot water cylinder. Is it just not needed or not advisable to have one (because it is unsafe, illegal as the builder said).

I wonder why plumber1 said what he said?

hot water in your unvented tank is pressurised from the cold feed, turn it off and job done, no hot or cold water.

so shouldnt be a problem to do your connections for cold and DHW just by turning that off. no need to mess with that at all if you are fitting rads.

 

[plumben]

I'm struggling to see why he would need to drain the unvented tank to connect into the hot,
As soon as you turn the main off on a unvested system the water stops

 

[Old Account]

As above mentioned G3 qualified engineer would be preferred - no headache no pain afterwards

 

[Rickster123]

As above mentioned G3 qualified engineer would be preferred - no headache no pain afterwards

Not preferred, essential.

 

[LCV]

Unfortunately I don't get to choose the plumber. Plumber1 is part of the loft company's team. Plumber2 is part of the builder's team.

 

[ShaunCorbs]

aslong as there is a stop tape incoming to the cylinder (which there should be ) post a pic up of your cylinder and someone can point it out, your fine

and just for added piece of mind put some decent valves on before taps and toilets

 

[Rickster123]

Unfortunately I don't get to choose the plumber. Plumber1 is part of the loft company's team. Plumber2 is part of the builder's team.

So it's not your house they're working on??

 

[LCV]

It is my house but I have gone for the main contractor route which means they have their own team of people, i.e. builder, roofer, plumber, carpenter etc.

I am 100% happy that I have gone down this route and I would advise anyone doing a full house renovation to do the same. It would have been a complete nightmare, unless you are an experienced property developer, to hire all the individual trades yourself.

 

[LCV]

Thanks ShaunCorbs I will do that. The scale of the renovation means we don't live on site so I will take one tomorrow and will post.

 

[chris watkins]

LCV
Lets get this sorted the valve on the hot water outlet is not essential so don't have it fitted, by the sounds of it it would be an extra anyway.
If it proves that it is necessary then it can easily be cut in afterwards by a G3 plumber at low cost.

To all of you who have claimed that hot water taps stop instantly after you turn the cold feed off on an unvented system have not had the pleasure of draining too many Megaflo (bubble tops) where the bubble acts like an accumulator. I have had some that run for 10+mins if you only have a tap or two on.

 

[Best]

It is my house but I have gone for the main contractor route which means they have their own team of people, i.e. builder, roofer, plumber, carpenter etc.

I am 100% happy that I have gone down this route and I would advise anyone doing a full house renovation to do the same. It would have been a complete nightmare, unless you are an experienced property developer, to hire all the individual trades yourself.

No offence, but if you are really 100% happy with your choice of getting builders to do both stages, - then why do you need to come on the forum to ask which, if any of the two plumbers was correct? If you had a G3 plumber that knows about plumbing systems, then they would have done it properly and give you correct advice.
If you know a good tradesperson, - use them, but if you want to take the risk of using builders who bring unknown tradespeople, so that you can have less responsibility, then sometimes you will have problems.

 

[LCV]

Best - I came on the forum because I have two plumbers giving completely opposite advice. So I wanted to get other qualified, G3, plumber's views so that I can decide on how to proceed.
I don't know any good tradespersons so that's why it would have been a nightmare to find all the required people that I could trust that are available exactly when you would need them on site during the course of the 1 year renovation project and for them to not hold up any other tradesperson's job.
Hiring a main contractor does not mean I have less responsibility, it is about managing risk and who is responsible for when something goes wrong. If you ever decide to renovate your own home you will soon realise when there is a problem that tradesperson is going to be blaming someone else.

 

[LCV]

Thank you Chris, your reply has been very helpful and sorted out my problem of what to do.

Also your comment about the draining time makes sense and I think plumber1 is right then with his 45min estimate. The house is over 4 floors, there are four bathrooms, kitchen and utility room so lots of taps!

 

[Best]

It is irrelevant how big the house is really. The water comes from the unvented unit, which will stop usually quickly if the supply valve to it is turned off.
I understand you getting a builder in to take all the trades jobs. However, you are gambling if you do not know the tradespeople. Plumbing particularly is one trade that builders seem to use poor materials and workmanship.
The fact you have been given conflicting advice from the two plumbers shows that at least one of them is wrong.