15 v 22 supply

[sunbeam]

hi

I need a new boiler to replace my netaheat

somewhere between meter and boiler, the 22 pipe has gone down to 15mm

I am told that its not recommended to feed a new boiler from 15 but to change the pipe is going to be hell on the house structure and probably very ugly and expensive with the fitting and all the remedial work and decoration after that will be needed.

is it necessary to have 22mm?

thanks

S

 

[gas4you]

Depends on the power of the new boiler, distance from meter, number of bends etc etc.

Only a site visit would give a definite answer.

 

[muggles]

Basically there needs to be a certain gas flow to the new boiler. Most new ones are 22mm pipe because that meets the requirements. Flow is impaired by bends, tees and the length of the run, so as Dave said the only way to give a definite answer is to look at your current installation. Your CORGI man will be able to do this.

 

[sunbeam]

Basically there needs to be a certain gas flow to the new boiler. Most new ones are 22mm pipe because that meets the requirements. Flow is impaired by bends, tees and the length of the run, so as Dave said the only way to give a definite answer is to look at your current installation. Your CORGI man will be able to do this.

Well the thing is, the Corgi man did come and said that the Netaheat's design meant he could not get a pressure reading at it. Apparently this old boiler has no 'valve' or something to tap into to read pressure.

Is this correct, will we only find out the pressure once the boiler is off the wall? It isn't a long run, about 5 m and I am thinking 1 x T + 2 x 90 bends - mains to the ceiling along the ceiling and down to boiler.

I really, really don't want to have to take the ceiling down. Accessing from above will be no picnic either!

Thanks

S

 

[giblets]

As has been said the gas pipework size has to suit the new boiler and has no bearing on the old one so testing that will mean nothing. The pressure has to be measured with the boiler running. Your CORGI man should know all about this.

 

[sunbeam]

As has been said the gas pipework size has to suit the new boiler and has no bearing on the old one so testing that will mean nothing. The pressure has to be measured with the boiler running. Your CORGI man should know all about this.

I don't understand, do you mean the present boiler? If so:

A it doesn't run that's why its being replaced!

B even if it did run, CORGI man says there is no access point on it to test pressure.

If you mean when the new boiler is in place and running, won't that be a bit late to be finding out the pressure is no good? It would all have to come down again and probably at my cost. And then there would be a delay while the pipes were changed, and its not getting any warmer in here!

Sorry, I am unclear. It sounds like you are saying the only logical way to proceed is to adopt a belt and braces approach and change the pipe in advance anyway. That is going to be awkward, ugly and so expensive. Surely there is a better way of going about this?

S

 

[giblets]

If you mean when the new boiler is in place and running, won't that be a bit late to be finding out the pressure is no good? It would all have to come down again and probably at my cost. And then there would be a delay while the pipes were changed, and its not getting any warmer in here!

Sorry, I am unclear. It sounds like you are saying the only logical way to proceed is to adopt a belt and braces approach and change the pipe in advance anyway. That is going to be awkward, ugly and so expensive. Surely there is a better way of going about this?

Your CORGI man will know what the gas input requirement is of the new boiler that he proposes to fit. He has to ensure that there is a maximum of a 1mb pressure drop between the gas meter and the new boiler. He should be able to carry out calculations based on the new gas input and the existing pipe run and fittings together with other installed gas appliances to confirm whether or not the existing pipework can be re-used. If the new gas rate cannot be supplied through the existing pipework then a bigger pipe will be required. This may not be needed all the way back to the meter as it is possible that the existing pipework has been reduced to 15mm quite close to the existing boiler and that only this section needs to be changed.

Not knowing your installation it is rather difficult to comment further but, for example, if the existing boiler is wall-mounted in the Kitchen and the 15mm pipe comes up from the floor to the boiler, it may be that the pipework under the floor may be in 22mm (or if an older house 3/4" iron pipe). I think your man is either being very cautious or needs to look further to see what can be done (if he can be bothered to).

 

[sunbeam]

Your CORGI man will know what the gas input requirement is of the new boiler that he proposes to fit. .

I see what you mean. The pipe actually runs through the kitchen ceiling before dropping down to the boiler and it may be, as you say, that it converts to 15 quite close to where it enters the kitchen. To discover that though means either pulling up carpet and boards above or hacking lumps out of the ceiling!

So you think that he should not have to guess and that it should be possible to accurately ascertain the pressure non-intrusively? I dont want to 'pressure' him with all this but i really dont want a new pipe run unless i am sure it is needed. I want to feel that he is doing a new pipe run as the only solution. This boiler replacement is already ballpark quoted at a staggering £2000 plus and extra work like that is going to add even more money as well as drastic mess and inconvenience.

S

 

[giblets]

I see what you mean. The pipe actually runs through the kitchen ceiling before dropping down to the boiler and it may be, as you say, that it converts to 15 quite close to where it enters the kitchen. To discover that though means either pulling up carpet and boards above or hacking lumps out of the ceiling!

Cheaper and easier than running a new gas pipe if it is found that one is not needed!

So you think that he should not have to guess and that it should be possible to accurately ascertain the pressure non-intrusively?

Quite right but pipe size not pressure. The correct pressure will come with the correct pipe sizing.

I dont want to 'pressure' him with all this but i really dont want a new pipe run unless i am sure it is needed. I want to feel that he is doing a new pipe run as the only solution.

I can't speak for him but I would prefer to minimise my workload if possible rather than struggle to run a new gas pipe if it is not required.

This boiler replacement is already ballpark quoted at a staggering £2000 plus and extra work like that is going to add even more money as well as drastic mess and inconvenience.

TBH £2k seems a very reasonable figure bearing in mind what we have to do meet current regulations.

 

[sunbeam]

Cheaper and easier than running a new gas pipe if it is found that one is not needed!

Heh! Well is it though? The ceiling is almost brand new and full of downlighters Id cry to see that ripped down. Upstairs is half teak flooring and that would be a sorry sight ripped up too. He is suggesting going through a wall, crossing the ceiling visibly with the pipe for about 4 ft, then going through the wall to the outside, running along the outside wall, and then coming back through the wall again! This may be cheaper than pulling down my ceiling but still not entirely ideal

So what it comes down to is if we cant see whats going on in the ceiling without making some seriously expensive holes (which may not reveal much anyway and we may have to make a load more) it's best to assume the pipes wont do the job and do the new run the cheapest, if not the most elegant, way possible?

Its enough to make me want to just get the netaheat somehow patched up so it limps on for a few more years.. This is all snowballing terribly

S