biasi garda he low pressure and lots of questions

[deskmonkey]

hi everyone.

i'm at my wits end so please stick with me whilst i try to describe my problem (there may be frequent breaks whilst i count to ten).

our house is undergoing an extension and we have just had gas central heating installed. we were previously on a storage heater (yes just one) and a gravity fed emersion tank.

the heating side of things seems fine with the pressure sitting around 1bar and all 6 rads are warm when they should be.

the domestic water is another matter though.

the plumber has made use of the existing pipes to take the cold feed to the boiler so the arrangement is this:

Riser - Kitchen Sink Cold Tap - Out Side Tap - Cold Feed for Washing Machine - Toilet - Bathroom Sink - Bath - Shower - Boiler

is this a common way of connecting things? So the boiler gets the cold feed last?

if you turn the hot tap on in the kitchen, it's less than half the pressure of the cold from any other tap and if you run a cold tap and hot tap together the hot almost turns into a drip.

since i pointed out the low pressure the plumber has returned and removed a small yellow restrictor from the boiler but it's made no difference.

he told me we have low water pressure in the area so i've called severn trent for a visit (still waiting for an appointment) but i got a pressure gauge today and it says were at 3 bars for hot and cold (with all taps closed).

the reason why its all so frustrating is the plumber was recommended by our builder, who happens to be my father-in-law (i think he hates me) and the plumber is his step-brother.

i had a really bad feeling about things when my father-in-law said the plumber was ok but he wouldn't use him!

thanks for any advice you can offer and for reading all the way through.

deskmonkey

 

[Agile]

It seems as if the plumber failed to measure the flow rate into the house and discuss the combi boiler option with you.

The static pressure is irrelevant, its the dynamic flow rate which matters! You need about 14 li/min minimum to use a combi boiler.

The plumber is quite knowledgeable about boilers as he has managed to locate and remove the flow restrictor. In spite of what you say that should have made a minor improvement.

Applying Kirchovs laws the remaining flow available for your hot water will be very reduced if any other tap is used. Its not at all ideal but the existing plumbing is usually very difficult to change.

An improvement could also be obtained by fitting flow restrictors to the prior outlets but at the cost of reducing flows there.

The only full solution is to replace the incoming water supply pipe. Depending on the distance from the main to your property this usually costs £1000 upwards.

Tony Glazier

 

[deskmonkey]

thanks for the reply.

i had it in my head that my biggest problem was volume of water not static pressure but didn't know had to express the idea.

how can i check my flow rate?

just checked the static pressure again out of curiosity and it's now up to 5bar being off peak.

i'm really confused about things as the boiler is less than 25ft from the riser (as the pipes run).

the kitchen with the riser is at the front of the house on the ground floor and the boiler is in the hall way next to the kitchen with the bathroom above it.

the plumber didn't remove the restricter on his own, he had his corgi mate with him and they had to call biasi and ask if there was one they could take out.

i didn't mean to sound like another guy watching over a workmans shoulder and contradicting everything he did or checking up on him when he left but we had 2 leaks on the domestic supply after he did his thing and both of them were speedfit elbows he didn't push home fully.

he tried to fit a towel rad in the bathroom and had to drill the holes twice because he got the centers wrong and then found out the rad didn't have all the brackets to mount it.

when he went to swap it the rad was discontinued so he got a totally different one so more holes were needed.

i asked him about the availability of a tool to check flow rate or static pressure and he told me they only do gas ones and you can't measure pressure/flow for water.

when i asked him about the water pressure he just sucked in through his teeth and said 'that's odd, it shouldn't be like that' but i've not heard from him since.

oh and as he's 'family' it's taken him about 3 months to do everything between real jobs. he's charged us £1000 so far and we bought the boiler up front.

deskmonkey

 

[Agile]

I am being less impressed now. Perhaps "having his CORGI mate there" implies he is NOT CORGI registered himself, thats illegal!

Next he is using speedfit, that smacks of an amateur, and if he cannot use it properly thats worse!

Flow rate is a function of the static pressure and the resistance.

Its easy to measure flow! Turn on a few cold taps and LEAVE them on !

Take a one litre measuring jug and time how long it takes to fill one litre from each tap. Do a little simple maths, eg six seconds for one litre is 10 litres per minute. Add the flow rates for all the taps and thats the open pipe flow rate. The dynamic flow rate is the flow rate when say 0.5 Bar pressure remains in the pipework.

Tony Glazier

 

[ChrisR]

you can't measure pressure/flow for water.

It stands to reason, it's a well known fact..!

 

[Slugbabydotcom]

Have you checked the obvious ie. Is the mains stoptap fully open and of course any valves between there and the combi? Is the valve on the mains supply outside fully open? Not unknown for kids to turn them off for a laugh!
What is the neighbours water flowrate like compared to yours?