Flow rate / regs query

[JD1]

Hi, not sure if I am in the right place but need a bit of advice please!

We recently had a new combi boiler installed, the engineer didn't take flow rate readings and instead relied on the ones he took over a year ago. Is this within regs? I would have thought they needed to do new readings shortly before the install took place. I have tried to Google but can't seem to find what I want.

We are now having massive issues with the water pressure, particularly the upstairs shower and the gas bills are huge, presumably because there isn't enough pressure going into the boiler, its inefficient and having to work twice as hard. Am I right in thinking this or totally off the point?

Having trusted the professionals we are now in a long running battle with the company to get this resolved so would like to know a bit more to counter their arguments, if we can.

Thanks in advance.

 

[Robert Tyrrell]

Easy enough to check the shower really. Just get a cheap replacement from Screwfix (other stores,are available)but make sure it has the same pipe centers, and that it works with less than 1 bar pressure.
You could also fit a shower power booster pump inline, on the cold supply to the shower.
As has been said, if the two sides of the shower don't have a roughly equal pressure then your thermostatic cartridge isn't going to,work correctly.

 

[Riley]

Not sure you can pump an already pumped mains?

 

[Robert Tyrrell]

Not sure you can pump an already pumped mains?

You might well be correct in your assumption there, but what I actually meant to write was:

"You could also fit a pair of shower power booster pumps inline, on the cold supply to the shower in order to bring it up to the same pressure as the hot from the combi."

In my defence I will state that I went to the pub last night

 

[Riley]

I think flow in general is the problem here mate. I don't think you're going to squeeze anything more out of what is already a badly installed boiler

 

[Fowlersrs]

This is pretty simple stuff. Your original installer really has let u down by not taking adequate readings prior to install if the combi. There's no 2 ways about it. They should of atheist made you aware that the boiler would only work at a reduced rate until you resolved the problem with the supply. I would press to get that resolved by the way especially of its not your responsibility as it'll help massively. Adding pumps to combi systems is just a complete work around tbh..

As for the shower pretty sure it isn't combi compatible if it was one with a pump inside on a gravity system. Again another basic check before installing a combi. I've seen them blow completely when put under mains pressure as they're just not designed for it so no wonder it doesn't work.

All in all sounds like you've definitely been let down, get ur supply pressure sorted though and a new combi compatible mixer and you'll be away.

 

[JD1]

Just thought I would update you all.
The company have finally sent a plumber and an engineer out.
The plumber identified that the valve that controls the shower is not a thermostatic control as originally thought.
The hot supply for the shower comes from the combi boiler and takes water directly from the new combi boiler. The old system was set up so the cold water was gravity fed (think someone mentioned it might be this in a reply) from the communal cold water storage tank for the block of flats.

As the hot is running from the combi boiler it has mains pressure whereas the cold water is gravity so does not have a constant pressure as it therefore fluctuates.

If the valve was thermostatic (the shower was already here and worked fine with the old boiler system) it would adjust the amount of hot and cold water coming out of the shower unit to suit the desired temperature.

A non-thermostatic unit doesn’t – it opens each supply by a set amount depending on where you have the dial. As the pressure and flow on the cold fluctuates it will then mean that the temperature of the water fluctuates in turn.

Their solution to this is to re-pipe the cold supply to the shower so that is fed off mains supply. They tell us this will result in a standardised pressure and flow for both supplies which in turn will mean we get a much more consistent shower temperature without it fluctuating.

I suppose the other option is to totally replace all the shower etc and put a thermostatic unit in.

Should they known all this from the original assessment and not put a combi in, in the first place?
Grateful for thoughts if you have some time.

 

[Howsie]

An you'll be wanting a thermostatic shower fitting...