Water pressure too low

[Gasangel]

Hi everyone

Hope you can help, I fitted. Combi boiler last week, when I done the quote I used a flow cup on the downstairs tap and from what I can remember it was fine.
I have converted the system from a system to combi boiler, the new boiler needs 14.5 litres a minute it's getting about 13, now although it's under it's just under, and having fitted 100 s of combi's I fully appreciate the flow rate problems with comb is but when one tap is open downstairs the other tap downstairs, is maybe at 30% flow rate and the bath tap has absolutely no flow rate.
The main complaint is the bath and the shower that they plan on installing this month won't work properly.
All header tanks have been cut out.
The hot water pipe is completely in 22mm except for about 5 metres which We have reduced to 15mm, would you advise increasing the 15mm in to 22mm or do you think the result will be minimum, the 15 mm is all upstairs, however when I say it's all 22 the downstairs is 15mm.
Do you think the house may be fitted with a pressure reducing valve ( built in 70s) and if so Ny ideas where it may be located?
Any advise will be greatly appreciated, as I don't want the customers to fork out a fortune to the water board. Cheers

 

[Gray0689]

It's your problem you fitted the wrong thing
If there a PRV it will be on incuming mains look for it can't be that hard to find if there!!

 

[Gasangel]

It's your problem you fitted the wrong thing
If there a PRV it will be on incuming mains look for it can't be that hard to find if there!!

How exactly did i fit the wrong thing??, They were getting a combi regardless as they ewanted the tank cupboard for a shower and they wanted the header tanks out also. Im not getting the blame just want to give them all the options i can.

 

[Bartdude]

What are the pressure and flow measurements on the cold main? If they're not adequate then a combi will never work properly.

I would expect to find a PRV near the main stopcock but it could be anywhere.

 

[Mustard]

if there is no PRV in the flat then fit a mains booster pump you can fit it on the incoming mains there not bad get a incoming pressure reading then check then get the booster you need what size boiler did you fit

 

[Gray0689]

How exactly did i fit the wrong thing??, They were getting a combi regardless as they ewanted the tank cupboard for a shower and they wanted the header tanks out also. Im not getting the blame just want to give them all the options i can.

Well if it is wrong flow then you should of let them know it would not work very well

 

[Gasangel]

Thanks for the replies guys.

Thats just the thing i done the quote about a month before the job and i tested the flow and i thought it was fine otherwise i would have mentioned it i have before.

But regardless of that, the fact is that its maybe 3 litres per min under, so whatever method i use it only has to boost it by a few litres per min.

The combi is a 30kw ideal logic +.

The booster pump - what sort of size is the pump as the ones i have looked at are pretty big, i couldnt trouble you for a link could i?

Cheers

 

[mikegas]

Boosting Mains Water to a Combination Boiler - How To Pages

 

[Gray0689]

There all pretty big and expensive for a decent one
Google and you will find no link sorry

 

[plumberdarren]

You can only pump up too 12ltrs a minute direct of the mains , anything more you will need a break tank .

 

[Centralheatking]

To plumberdarren I know your right about the breaktank but where did you get the 12ltrs per min ?

What I mean is where in water regs - thanks in advance

As below I thought it was verboten

 

[WaterTight]

i didn't realise you could pump the mains - everyone keeps saying it's illegal?

 

[plumberdarren]

Section 3.15 water regs says written consent is required from the water undertaker if a pump is connected directly or indirectly to a supply pipe which is capable of pumping more than 0.2 ltrs per second or 12ltrs per minute.

 

[plumberdarren]

So basically under 12ltrs min is okay but you would get that on most mains anyway.

 

[WaterTight]

ahhhh
Thanks

 

[Gasangel]

Yeah thats true about the break tank, i was wondering if feeding the combi from a header tank would help, im not sure, probably not but im going tomorrow, and am kind of banking on the pressure being under 1 bar or finding a prv

 

[wheeto]

So basically under 12ltrs min is okay but you would get that on most mains anyway.

Yes, it's to allow for high-pressure washers to be connected directly to the mains.

 

[RogerH]

you can get a complete packaged booser set from www.pumpexpress.co.uk or google Aquabox