Pressure Problem - 22m to 15mm supply a cause?

[mrchook]

We have just replaced our old combi-boiler with a new condensing model, and the plumber noted that we don't have great water pressure (but was just as bad before we replaced the boiler). For example, the electric shower in our 2nd bathroom provides only a scalding dribble if at the same time another tap is opened, or the washing machine is filling.

The plumber told me that a pump cannot be used with the combi-boiler, and wondered whether the mains stopcock tap (which I had discovered under some floorboards in the hall when relaying them) was fully open correctly. Otherwise he said that the only way to improve the pressure would be to fit a larger rising mains pipe from the road, and that this was a big job.

I have checked the mains stopcock - and it was fully open. HOWEVER, at the tap, the mains supply is reduced from a 22mm to a 15mm pipe. Would this cause a reduction in pressure for the whole house?

Advice appreciated!

 

[PEDANTICVINDICTIVEMAN]

If you allready have 22mm coming in and then reduced to 15mm with a 15mm stop tap, it might be worth removing the stop tap and checking wether it is full of shiitte and partially blocked, obviously switch off in the street first, oh yea also check wether stop tap in the street is fully open.

 

[mrchook]

Thanks for your help. The stop tap in street is definitely fully open - will check for ****e in tap under floorboards!

So a 22m supply pipe reducing to 15mm wouldn't in itself reduce the pressure to the house? (Sorry if this is a dumb question...)

Cheers

 

[PEDANTICVINDICTIVEMAN]

Might be worth changing to 22mm stoptap and run 22mm pipe as far as possible to other outlets.

 

[Paul Barker]

What do you do with sealed systems, take a rad off and pea in that?

PS sparkies pea on TT earths to make them pass a loop impedance test.

 

[chrishutt]

take a rad off and pea in that?

Don't give him ideas!

22m supply pipe reducing to 15mm wouldn't in itself reduce the pressure to the house?

The 15mm pipe will reduce the running (dynamic) pressure compared to 22mm, and hence the flow rate, but it sounds as if your pressure drop is greater than that.

You really need a proper plumber who knows how to check water pressure and flow. A search on this forum will give you more info - it's been discussed before.

 

[PEDANTICVINDICTIVEMAN]

Put your mouth over the end of the pipe and turn water full on, if it comes out of your nose pressure is reasonable, if it comes out of your ears and nose pressure is excellent and will run a combi, might need a doctor after the test though.

 

[DP]

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