combi installation

[hornchurch]

hello, would just like some advice on installing a new combi. The problem i have is the water pressure is only 2 bar and the flow rate at kitchen sink is 8lts/m. i have checked the flow rate at the main stop cock outside and is only 11lts/m. so i dont see the point in running a new water main.
At the moment it is a bungalow with tanks in loft but the owner is converting the loft into bedroom with en-suite, because of this i will lose the height for a tank to feed the en-suite shower. My plan was to put a break tank at low level in the loft feeding a wilo whole house pump to run the combi and colds off. A friend has suggested to me a cheaper way by installing a 300ltr vessel in loft connected to the mains which will act as a pressurised store. would like to know if anyone has tried this and is it likely to increase the flow rate by much? As usual the owner would like the cheapest but best option so want to get it right first time.
thank you.

 

[Gasguru]

Have you checked the neighbours property for flow/pressure?


AFAIK the legal minimum flow /pressure is 1 Bar and 9 litres/min. Are you sure a flow rate of only 11 l/min is not due to a blocked/scaled service pipe of faulty boundary stopcock?

Have you checked the flowrate at the outlet of this stopcock.

Break tanks (which in this case would have to be large capacity to keep up with flow) and accumulators are not going to be a low cost option. 2 Bar may be a too low for and accumulator to worthwhile.

 

[gas4you]

with this really low flow in the kitchen I agree that there may be a blockage. 8 l/m is not really enough to even give a good supply to a 24Kw combi. If the problem cannot be solved then I think you will have to find space in loft for new larger cold storage tank and stick to gravity hot and cold in bath/shower.

Waste of money fitting an un-vented cylinder with this pressure/flow rate.

 

[hornchurch]

Have you checked the neighbours property for flow/pressure?

[/quote]

ok thanks for replying, i have checked the neighbours flow rate which is 15lts/m at the sink. Im only getting 11lts at the main stop cock in the road.
Have spoken to the water board and because there is 2bar of pressure they say it is not a problem. They have though agreed to replace their stopcock for free, think this an excuse to fit a meter!
I assume the problem is between their stopcock and the supply in the road, which they say they will replace for five hundred pound!
I was thinkikng a cold water storage vessel (cold stream) would be a cheaper option but have never tried it an am not sure how much it would increase the flow?
And would it be ok to run a combi off this?
Havent got the height to fit a gravity system in, there is only room at floor level to fit a tank in loft and there is a shower going in the en-suite in the loft conversion.
Has anyone got different ideas?

 

[Gasguru]

Have the stopcock changed for free - it may just be full of debris.

If it still doesn't improve then provided the pipework from the boundary stopcock to the house is OK I would say the new connection for £500 is the better bet. Get them to tell you the flow/pressure the new connection will provide. No noisy pump and break tank setup.

There are no cheap options. Privatised utilities have to make vast profits - providing a decent pressure/flowrate is not their priority hence they still comply with only 11 l/min which is above their contractual minimum rate dspite it being inadequate.

 

[peter the plumber]

hi hornchurch i live in hornchurch essex .The pressure round here is usally ok to fit a combi .I have found about 2.5 to 3 bar 15litres a min .Where abouts in hornchurch are you having probs pete

 

[hornchurch]

Hello peter, the job is in Laindon Essex and i have been in to two properties down the same road and one is 15L and the other is 20L/min at the kitchen sink. seems the problem is between the outside stopcock and their main supply in road. The owner wants the problem resolved but is reluctant to hand over five hundred quid to the water board for them to replace it. so wants me to come up with a solution!