Low burner inlet gas pressure to ch boiler

[midge]

A colleague has an older atmospheric burner fired gas boiler which although working fine is near the end of its life.

The problem is that the meter is 400 metres away down a long drive, piped in 2" steel to the house. Although there is 23mbar at the meter outlet, the appliance inlet pressure is 17mbar.

No one seems to want to change the boiler as it's below 19mbar. Obviously it has been wrong since being installed 20 years ago, but he's had a figure of in excess of £20,000 to trench and replace the 2" with larger PE pipe which is out of the question.

Is there any modern boiler range which can be suitably installed? as otherwise he can't see a way out other then oil or LPG.

 

[villa_tom]

I think Worcester state in their MI's that the boiler will function at a much lower inlet pressure. But although they state this I think you may still be hard pushed to get somebody to install with this problem.

 

[gaspastemania]

Worcestors do work fine at a lower inlet pressure from what i am led to believe , probably about the only decent thing about them !!

 

[SafeGasInstall]

wb only neeed as low as 15mbar....i will fit the boiler no probs 🙂

 

[Reg Man]

This will never be correct depending on your gas demand and if you are prepared to up size the pipe. No one should be installing a new appliance to an inadequate gas supply. The manufacturer instructions will state that the gas installation pipe must be installed in accorrdance with BS6891. This British standard requires a dynamic working pressure differentail of no more than 1mbar between the meter and the appliance under full load.

On the positive view point. You have 400 metres of 50mm pipe which is inadequate in size. You may be able to replace a proportion of this pipe rather than all, to meet the requirements. First you need to find out your demand metre/cube/per/hr. From the figures you have stated your demand is higher than the average domestic installation.

 

[tamz]

Your boiler input with those figures must be near or over 150kw. Big house. U16 meter may be too small for what is needed.
Couple of options.
The existing boiler "may" be oversized. Fitting a lower output boiler would keep the pressure drop within limits. This would need to be measured up and calculated by the installer.
Contact the supplier for a quote to move the meter nearer the house.
Hire a JCB, dig a track and lay your own pipe. (your land your pipe) and get someone to connect the ends.
This size boiler is in I&C territory. Any decent I&C contractor should be able to advise on the best solution.
No option is cheap.

 

[gaspastemania]

From what i am led to believe from gas safe you cant touch a gas pipe unless your gas safe registered,that includes if some lays it and doesn't connect the ends .

 

[ferret]

2" supply should be more than adequate , do as tamz says or check with supplier than meter is capable of supplying the volume needed to reach the property if no other way look at a gas booster pump being fitted in the property ,

 

[Reg Man]

2" supply should be more than adequate , do as tamz says or check with supplier than meter is capable of supplying the volume needed to reach the property if no other way look at a gas booster pump being fitted in the property ,

You can't say that with out knowing what there is and what is required.

I've done a little rough calculation. For a demand of 5metre cube/per/hr, thats about 40kW input at this distance on a clean straight 50mm pipe, the dynamic pressure differential will be approximately 2 mbar. Guessing that if you have a 400m drive you may be on the higher end of domestic consumption.

 

[stevetheplumber]

400m of 50 mm whats the permitted drop on that ?

 

[Billy Bob Bob]

400m of 50 mm whats the permitted drop on that ?

alot,put the gauge on for a tightness come back next week,50mm pipe work thats a big pipe dont think that will fit in my hilmors lol

 

[SafeGasInstall]

non domestic ticket holder job this is and will cost a lot

 

[SafeGasInstall]

I think it will be cheaper to build bungalow next to the meter and fit boiler there and have booster pump to the house in 2" flow and return 🙂

 

[tamz]

0.5mb on a water guage over a 4 min test assuming it is a straight length of pipe

 

[ferret]

now it could be that all this is for nothing ! if the existing install is 2" steel from meter to property no one has said what it is once its in the property , it may only be the pipework inside thats too small ie 15mm copper or 1/2" steel to the existing boiler which would give you the wrong inlet/wp of 17mb ???

 

[Reg Man]

Thinking about this situation. We can disregard BS6891 its outside the scope. We are into the scope of IGEup/2 for pipe install.

 

[Reltub]

I agree with ferret, the pipework in the property may be incorrectly sized, also any other appliances in the property and what size is the boiler?

 

[Reg Man]

400m of 50 mm whats the permitted drop on that ?

1mbar from the primary meter to the down stream appliance for pressure of 21mbar. For design working pressure's above 21mbar you are allowed 10% differential. For this length and size of pipe your looking at approximately 2 may be 2.5metre cube/per/hour appliance.

On site survey required to find out what is required and how much pipe needs to come out and be replaced.