Gas pipe to boiler

[dp123]

I think i shouldn't take advice from unqualified people

Are you competent to make that decision?

No.

Now to be serious for a moment.

Today we had a new engineer visit to give us a quote.

He looked at the meter then behind the cooker and at the boiler.

He pointed out to the wife the 15mm pipe and said this was too small.

The wife told him the last installer had also pointed this out but had not looked at the meter and then informed us we needed a new 22mm pipe from meter to boiler.

The installer said he doesn't think it is necessary to take the pipe all the way from the meter as in his opinion the 22mm pipe was likely to run the full length of the house.

He said rather than risk it he would suggest adding a T piece where the 22mm pipe exits the wall behind the cooker and running it to the garage from there.

The wife said this would be much better than the suggestion the first installer made as it would mean we didn't need to have the floorboards taken up in the living room,also both the under stairs cupboard walls will not need to be drilled to take the pipe to the kitchen.

My only worry having read all the posts in this thread is that using the T off the other pipe may not be the solution,i hope i am wrong and probably am.

My question is if he just adds the T to the existing pipe and blanks the old pipe off at the garage (the 15mm pipe end) is this not like adding another 8 meters to the existing pipe?
Logic suggests it will make no difference as the old pipe is full of gas so the new run will not be effected.
As i said i hope i am wrong.

Over to you.

....

 

[Gasguru]

Is the cooker all gas or duel fuel ie just the hotplate gas? If gas is it a double oven?

From your previous posting the cooker appears to be 6m from the meter. Is that a direct route or the actual measured pipe lenght route? It is likely there are several bends in this pipe running back to the meter adding the equivalent of say 3m lenght to the pipe. Therefore the pipe lenght is perhaps 9 or 10m.

If the cooker is all gas this is likely to result in at least a mbar drop in pressure from meter to cooker point when both appliances are on full load.

Therefore even if he proposes to run 28mm from the cooker point to the boiler I suspect it will still result in a drop considerably more than a mbar.

What make/model boiler are the installers proposing to fit?

As has previously been stated the calculation tables are wildly adrift from reality so accurate calculation is difficult. Give it a go in 28 and see, if it drops only a few mbar most installers wouldn't worry; round my way most wouldn't worry if it droped 10 mbar.

 

[cowboyplumber]

You boys have been keeping things busy, while I been in Mexico. Very interesting pipe fitting over there, pipe clips don't seem to have made it down there yet .
My six peso's worth is that PULLED bends make an incredible difference to gas flow rates. If you can get a pulled bend straight off the meter union, then you'll have little problem with pressure drop.
Except when you do

 

[dp123]

Is the cooker all gas or duel fuel ie just the hotplate gas? If gas is it a double oven?

Its all gas but not a double oven.

From your previous posting the cooker appears to be 6m from the meter. Is that a direct route or the actual measured pipe lenght route? It is likely there are several bends in this pipe running back to the meter adding the equivalent of say 3m lenght to the pipe. Therefore the pipe lenght is perhaps 9 or 10m.

I don't know if its direct or not as its under the concrete floor, the cooker and gas meter are on the same wall of the house so I'm hoping it is.

If the cooker is all gas this is likely to result in at least a mbar drop in pressure from meter to cooker point when both appliances are on full load.

Therefore even if he proposes to run 28mm from the cooker point to the boiler I suspect it will still result in a drop considerably more than a mbar.

I'm totally confused (yea it don't take much)
The first guy (the one that didn't notice the meter pipe was 22mm) said a full run of 22mm would do the trick.
This second guy says a run of 22mm from the existing cooker pipe will do the trick.
Now you are saying even if he fit 28mm it may still not do the job.

What make/model boiler are the installers proposing to fit?

I'm not sure, he did the measurements e.t.c. and said he then gives them to his boss, his boss then prices the job up,we should hear before Friday.

 

[chrishutt]

PULLED bends make an incredible difference to gas flow rates.

Not according to the tables. An elbow has an equivalent length of 0.5 metre while a bend has an equivalent length of 0.3 metre. Difference 200mm of tube - hardly justification for pulling a bend.

 

[Balenza]

PULLED bends make an incredible difference to gas flow rates.

Not according to the tables. An elbow has an equivalent length of 0.5 metre while a bend has an equivalent length of 0.3 metre. Difference 200mm of tube - hardly justification for pulling a bend.

Yes but can you really believe that an elbow is as low as 0.5 according to these tables . Id have to agree with cowboyplumber.
In any case you lose two joints when you pull a bend.
You'd never get away with using elbows on a hi-spec fridge system .
The Engineers would be down on you like a ton of bricks.

 

[cowboyplumber]

Are you daft Chris?
I am talking about the real world here, not stupid tables, that we all agree are inaccurate.....

 

[dp123]

I have now had a second estimate the prices were near identical.
The first installer will be fitting a Ariston HE 30 FF combi and the second a Potterton 24 Eco HE combi,which one in your view is the better boiler?

 

[Gasguru]

Is that an Ariston GENUS HE 30 FF, is this an updated ACO can't find anything on the Ariston site. It's a more advanced boiler ie more difficult for fault diagnosis, more complex to work on, probably requires definate service every year (primary heat exchanger aluminium) and to qualify for the warranty, not a lot of experience out there since a fairly new design, Some Aristons are so crammed together they're a b*ger to work on. I'd avoid.

I'm no fan of Potterton but it's very easy to work on and diagnose faults, a boiler thats been out for many years with the addition of an extra heat exchanger to improve efficiency. Should go a few years before simple servicing. Merchants will stock more parts than the Ariston. Use the search and you'll see all the common faults.

 

[dp123]

Its the Clas HE 30 FF that he has quoted for,they make a 24 FF a 30 FF and a 38 FF

 

[Gasguru]

No idea what an Ariston Clas is. The Aco and Genus are not that old so I guess the Clas is the next version (ie cheaper to manufacture and not long out in the field).

Given that and as I still think the gas pipe will be undersized, the Potterton will be a safer bet than the Ariston (which incorporates the latest burner technology and often give problems with undersized gas pipework.)

Others may have come across the Clas.....nothing on Ariston or MTS websites.

 

[namsag]

If you are going for the potterton performa get the 30he far better hot water delivery as opposed to the 24heand not much dearer,simple and very reliable boiler very easy to work on and when it does break down cheap parts and easily diagnosed

 

[ChrisR]

Agree with nam again there.
More demanding on supply pipe of course!