70m from meter to boiler!

[Richard Olafsson]

Hi All,
I've just moved into an old house which is currently served by an old boiler for central heating and hot water, we estimate it must be about 70m of 28mm pipe to the boiler from the meter across a shared access bit of land. From the name it looks like a 40kW boiler (Chaffoteaux & Maury Corvec 1.140).

None of the tables go above 30m for pressure/flow drops and I am aware that newer boilers need more gas flow than the old one potentially does. Is there a way of measuring flow/pressure at my existing boiler to make sure the gas supply will be up to the job of a newer one? I'd rather know before spending out on a whole new system and then have to mole out for a new gas line and other expenses...

Thanks!
Rich

 

[Rob Foster]

Hi All,
I've just moved into an old house which is currently served by an old boiler for central heating and hot water, we estimate it must be about 70m of 28mm pipe to the boiler from the meter across a shared access bit of land. From the name it looks like a 40kW boiler (Chaffoteaux & Maury Corvec 1.140).

None of the tables go above 30m for pressure/flow drops and I am aware that newer boilers need more gas flow than the old one potentially does. Is there a way of measuring flow/pressure at my existing boiler to make sure the gas supply will be up to the job of a newer one? I'd rather know before spending out on a whole new system and then have to mole out for a new gas line and other expenses...

Thanks!
Rich

Ok this big one and might be an outside the box question, I will have to consult with some old farts I drink with
Stick with us
Rob Foster aka centralheatking

 

[ShaunCorbs]

Commercial job you would be looking at around 54mm 2" at that length

Best option move the boiler or get the meter moved onto your land

 

[Riley]

Yeah too high a pressure drop over that distance

 

[ShaunCorbs]

TBH I wouldn't be surprised if it's been down rated to around 25-26kw

 

[Richard Olafsson]

Been out to the meter again, it's a U6 and the main underground run is plastic pipe of about 35mm OD..

 

[ShaunCorbs]

Been out to the meter again, it's a U6 and the main underground run is plastic pipe of about 35mm OD..

Will be 32mm mdpe (yellow)
That will just about do then if it's properly connected just for the boiler no cooker or gas fires etc

With the current setup eg ranged rated etc

With a new true 40kw boiler it won't sorry to say

 

[Last Plumber]

It should be OK with 35mm (1 1/4") will do if your 70M includes allowances for bends and there are no additional appliances.

 

[Riley]

Still tight though isn’t it??

 

[ShaunCorbs]

It should be OK with 35mm (1 1/4") will do if your 70M includes allowances for bends and there are no additional appliances.

Ok In steel but not plastic

 

[Last Plumber]

Ok In steel but not plastic

View attachment 35340

I didn't mention plastic.

 

[ShaunCorbs]

I didn't mention plastic.

So needs to be re run as ops run is plastic

 

[Last Plumber]

So needs to be re run as ops run is plastic

I'll make it clearer!
If it's already been run in 32mm plastic below ground over a distance of 70 Meters, I doubt that it will be large enough for a 40 Kw Boiler if we need to have a 1 mb maximum drop in pressure.

However, If I were doing the work I would first of all check the pressure at both ends of the existing pipe. I would then assess the situation and make a decision as to whether or not the drop over that length warrants the pipe's replacement.
Should it need replacing with the next size of pipe up then I would do just that.

I had not read post 6 where he mentions the underground pipe.
I read this below where he mentions 28mm pipe so I thought of Copper tube and because it says 'across' I pictured an external pipe run.

we estimate it must be about 70m of 28mm pipe to the boiler from the meter across a shared access bit of land.

I am aware that newer boilers need more gas flow than the old one potentially does.

To the OP.
My advice would be to Get a Heating Engineer to calculate the heat requirements for your property. You may find that a smaller Boiler will do and that in turn may mean that the underground Gas pipe is OK.
I have not seen this obviously but I think facts and figures are the best thing to go off.

 

[Richard Olafsson]

OK, so to better clarify: the house main tap is in 28mm copper, the supply from the meter is underground under a church center car park in the yellow plastic (I'm guessing to mole a new run would get pricey?) A plumber did visit earlier and he was suggesting a 38kW Vaillant, the old one does keep us warm but we've only been here a week or so! He was suggesting to measure the actual supply but also upgrade the meter to a U16 to have the bigger fittings and fit the boiler right at the junction to the house to minimise internal losses and extra bends which are present in the current install..

 

[ShaunCorbs]

what are you planning on running via the gas ? as u16 is a big meter (around 160kw)

 

[Richard Olafsson]

what are you planning on running via the gas ? as u16 is a big meter (around 160kw)

Only the boiler, he was just suggesting that the bigger meter connections and pipework within the box would help..

 

[Last Plumber]

Is this a Vicarage?
Have you asked him to calculate the Boiler size?
I am not saying that it doesn't require 38Kw because I have not seen it but I would at least check.

What else is off the underground pipe?
What else is off the Meter?
Sorry for 20 questions.

 

[ShaunCorbs]

Only the boiler, he was just suggesting that the bigger meter connections and pipework within the box would help..

not really just bush it up, its not a volume issue eg how much the meter can supply but a pressure drop over the length

and plus that will cost you a bit for the networks to up your meter

 

[Richard Olafsson]

Yes, it's an old vicarage, technically a semi as a church house was built on to one side but it is big, 300 square meters over 3 floors. He had a tour of the house and 38kW was his initial thought.
The supply in the meter box Ts off to the two property meters, then it's the single dedicated line which only supplies the boiler. The church house only uses gas for the hob and fire as they have oil for heating.
I know what you mean about upping the meter size, it's only about a foot of the smaller bore pipe between the meter and underground pipe..

Thanks All for the help so far!

 

[chris watkins]

Richard would it not be a good idea to do a heatloss etc to find out exactly what you need? There maybe a number of measures you could take to live with what you have got (extra insulation, timings/ spilt load etc.) or absolutely not, as the case maybe. In which case it is an upgrade.

 

[Richard Olafsson]

It's an old listed place so we will be restricted to how much we can improve thermal performance, but improved insulation and hopefully double glazing will be done soon. The existing boiler is on its last legs so I'd rather replace it on my terms!

 

[Rob Foster]

I think we all know he answer, the supply is too small diameter,
Bite the bullet and improve it.
Watching a gas bioler fetch cause the gas supply is inadequate is not funny
Rob Foster aka centralheatking

 

[bill577]

Your in commercial territory as the volume of the pipework and meter exceed domestic , 0.035 cubic metres if I remember correctly.