Mains water pressure low

[wrighty208]

Hi there,
I've just had someone round to give me a quote for a new combi boiler (was looking at the worcester bosch 30si for a 3 bed terraced house with 1 Bathroom).

However, we just measured the water pressure and he thinks the pressure is a bit low - 3 Bar and about 10 litres per minute.

What are the minimum recomendations for these combi boilers? I was told about 12 litres per minute minimum for a decent shower.

Is there anything I can do to increase the supply - I believe I have lead pipes entering the house but I have checked my neighbours pressure and think his is the same as mine!

Cheers for any help!

 

[BoxBasher]

The static pressure will remain the same regardless of the pipe, it is the flow that will be affected.

The industry minimum standard (for incoming water supply) is 9 litres/minute at a working pressure of 1bar. 3 bar is pretty good, but pressure is useless if you cannot get a decent flow at the same time.

Different boilers and appliances may require more than this, although it should never be taken for granted that your supply will remain at a level higher than this standard.

If you have lead pipes then upgrading to a nice new 25mm Blue Polyethelyne pipe will increase your flow.
Are you on a shared supply with your neighbours? If so then you shouldn't really think about a combi until you have your own supply as your water flow/pressure will vary drastically as they use their water too.

Edit in italics

 

[wrighty208]

Hi, thanks for your reply.

I'm not on a shared supply with my neighbours - There is a stop tap in the front garden (by the property border) which goes straight to the house into the cupboard under the stairs. The pipe coming into the cupboard seems to be quite a large lead pipe (not sure on size - could be 22 or round abouts!) - but then there are 2 stop taps next to each other with a 15mm copper pipe feeding the house.

Do you think 10 litres/minute will be ok for a Worcester Bosch 30Si? (I'm quite keen to put in a combi condensing boiler for a few reasons:-

1. Currently have an old back boiler (Baxi) and the fireplace looks VERY old!! (although probably about to come back into fashion!!)

2. Hot Water is gravity fed so the shower isn't the best!

3. I'm probably wasting a lot of stored hot water

4. I just recieved a £330 gas bill when the heating is only on for an hour in the morning and between 6-11 in the evening! (Thermostat at about 17 degrees)

 

[BoxBasher]

Do you think 10 litres/minute will be ok for a Worcester Bosch 30Si? (I'm quite keen to put in a combi condensing boiler for a few reasons:-

I'm not a Boiler man so can't give you advice there. There should be minimum requirements on the MI's or on the WB website.

Lead pipe may appear to be quite large, but is fairly thick walled so the internal bore can be considerably less than the outside diameter.
Lead is also prone to scaling/furring up and is therefore quite a rough bore pipe, leading to higher flow loss (friction). It can also start flaking/breaking down internally and when a piece flakes off it can catch on others and lead to very restricted internal bore causing more flow problems.

If you are going to the expense of having a new boiler then get the pipe done too. Better supply will mean greater efficiency and less problems in the future.

Don't forget that Combi's will slow the flow down in order to heat it up so you may end up with very poor flow on your hot water.

If your plumber has seen fit to bring it to your attention before doing the work then take heed.