New water mains pipe or accumulator in Potters Bar, Herts Update 11/9

grizgut11 · 29 Aug 2017

Hello All,

Please can anyone offer some advice re the above? I have an older combi W/Bosch 28cdi which is fine if we use the shower either very early in the morning or later in the evening when the water flow/pressure is O.K. If we use it in 'normal' hours (6.30-9.30am) we get fluctuating water temperatures and god forbid anyone uses any other tap or toilet in the house.

We've had the boiler serviced and had various parts replaced (heat exchangers etc) and a decent thermostatic mixer shower is fitted. Hot water to the taps is fine for a combi. I know combi's suffer if pressure/flow rates are poor so I want to try and improve the water supply before either getting a newer high flow rate combi or getting an unvented cylinder setup. We only have one shower (because of the problems above) but I would like a second shower in the downstairs bathroom that we could use at the same time as the upstairs shower, eventually.

I've read through lots of threads advising on how to improve flow rates and pressure, I've got about 2 bar static pressure and about 15l flow rate at the very best. At worst I'm looking at about 1.1 bar pressure and about 12 lpm flow rate (pretty much the top limit of the combi boiler anyway). I'm not sure how to work out the dynamic flow but I'm assuming it's bad?

I've got a 15mm incoming copper water main in the kitchen of a mid 50's built bungalow, 2 bathrooms and 5 adults. The question is will a new mains pipe guarantee improved flow rate or pressure or should I get an accumulator or even a pumped accumulator?

Many thanks for any input.

rob_j20 · 29 Aug 2017

Dynamic flow you run say the kitchen tap and measure the flow so say 14lpm. Then leave it running and read the pressure from another tap.
Then the two reasons give you say 1bar at 14lpm.

grizgut11 · 29 Aug 2017

Thanks Rob, I'll do this asap

St0rmer66 · 29 Aug 2017

Static pressure of 2bar will give poor performance from an accumulator. Not to say it won't work at all but they rely on a high static pressure.

dilalio · 29 Aug 2017

Where abouts in Potters Bar?
I live and work in PB and there's some areas with bad supplies... shared mains in the Little Heath area are a common pain.

rob_j20 · 29 Aug 2017

For those in the know what is a good range for incoming water, in sure when I last checked mine it was static pressure around 4 bar, dynamic about 14lpm at 3bar. 14 lpm max flow.

dilalio · 29 Aug 2017

Pressure is not as important as flow.
If you have a combi that can provide HW at 16lpm then you need to have much more than that at your Cold main... 18lpm+ is what you're looking for to get acceptable results.

grizgut11 · 29 Aug 2017

I'm in Sunnybank Road, right at the top by the old Sunnybank school. When we first moved here we'd get some summer days with no water at all (refunds from water company) but they renewed the mains pipes 10+ years ago and things improved a lot. We got a combi after a loft extention left very little room for a conventional boiler + cold/vented water tanks. We have still got some loft space above the upstairs bathroom but it would be very cramped, can't help thinking a conventional setup would be a better solution if it could be fitted in, perhaps using the combi as a conventional boiler?

dilalio · 29 Aug 2017

I was at 195 Sunnybank last week. I have a landlord there, who's house I look after. They have a combi with tenants in the property. Don't think they have an issue with it - haven't had calls regarding lack of HW flow. Sounds like it may be your main! The school grounds are being developed so if you're right next door, there may be scope for supply improvement.
Ask the supplier to come and measure pressure and flow at their stopcock.

Happyplumber · 30 Aug 2017

On domestic installs i normally recommend an upgrade of mains where ever possible. If this is possible and the easiest and least disruptive method is using a moleing company
Sizing accumalators and the space they take up can cause issues especially if you have large unvented cylinders .plus there is bothibg to service or check once a new main is installed

rob_j20 · 30 Aug 2017

We got a very rough quote of about £900 to run a new 25mm supply, from the main. From a company that can do the full connection as well. Currently its a 1/2" copper pipe. Do you think it would make much difference?

grizgut11 · 30 Aug 2017

Small world I'm non-adjoining next door to 195. I understand what you say about their combi but only a couple of weeks ago they did not realise that raw sewage was leaking from the drain on the drive outside their house ☹. With all the advice given above (thanks to all) it sounds like I need to get the pressure/flow tested at the mains outside to see if its worth upgrading the mains supply pipe to the house? Is this something the water company will do or do I need to call a specialist company?

Whoever tests the mains, I'll wait till the holidays are over as the water pressure/flow always drops away when everyone's back at work/school. If I understand correctly, whichever way I go with the heating and hot water the mains water is the first thing to check and/or upgrade?

bernardgreen · 30 Aug 2017

Happyplumber said:
Sizing accumalators and the space they take up can cause issues especially if you have large unvented cylinders

A cold water storage cistern in the loft is a low tech large volume "accumulator". Provided the mains pressure is high enough to lift water up to the cistern a cistern will provide high flow rates when water is needed irrespective of the mains pressure at the time., They make take a long time to refill when the mains supply pressure is poor or intermittant

Happyplumber · 30 Aug 2017

grizgut11 said:
Small world I'm non-adjoining next door to 195. I understand what you say about their combi but only a couple of weeks ago they did not realise that raw sewage was leaking from the drain on the drive outside their house ☹. With all the advice given above (thanks to all) it sounds like I need to get the pressure/flow tested at the mains outside to see if its worth upgrading the mains supply pipe to the house? Is this something the water company will do or do I need to call a specialist company?

Whoever tests the mains, I'll wait till the holidays are over as the water pressure/flow always drops away when everyone's back at work/school. If I understand correctly, whichever way I go with the heating and hot water the mains water is the first thing to check and/or upgrade?

Find a local company who can Mole the new supply in ,this will cost you less then half the price of an accumalator normally and also there are no ongoing costs such as diaphram packing up or needs to be changed,servicing or breakdown costs .

grizgut11 · 30 Aug 2017

Presumably I need to make sure the mains pressure in the street is going to make a new mains pipe worthwhile? This is all in preparation for a new heating/hot water system, hopefully.

Any recommendation for a boring company that could do the entire job?

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New water mains pipe or accumulator in Potters Bar, Herts Update 11/9

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