I have just had my boiler replaced, and converted from gravity to mains, unvented water system. I did have a booster pump on my shower, however the plumbers say that this cannot now be used, but I am not happy with the performance from the shower.
mains pressure shower
- Thread starter paul_round
- Start date
your plumber is correct you cannot pump a normal mains supply 
OK, can the mains pressure be increased with a pump?
paul_round said:
Kev has already said.....NO
Your hot pressure should be good with an unvented system. Your cold pressure is affected by size of incoming pipe and pressure pumped out by your water company.
Ask your plumber to check the installation as I believe unvented are at 2 bar+ and should be more than ample.
Perhaps your shower needs attention!
Pressure is OK, it's just that it was a power shower, (with the pump on the old system)wheras now it's not a power shower.
flow rates from combis always the customers main grumble, i normaly stress that now water has to be heated as you have shower as before water already heated and waiting to go in cylinder, combis like showers generaly the greater the kw(btus) the better the flow rate
It's not a combi boiler, and we have an stainless steel hot water cylinder
paul_round said:
mains unvented what hot water supply or central heating curcit
Thats an unvented cylinder with a 'system boiler' I guess
A competent installer [one issued with a photo ID card] should be able to fit a balancing tee so that you have equal pressure at the shower to reduce risk of scalding. This is not something you can do yourself.
It brings question on your installer if he did not offer to provide a balanced supply and I wonder if he was qualified to fit it.
Has the installation been registered with the local authority and benchmark booklet filled in?
I don't have a problem with my plumber, We have used him before and he was recomemended, the pressure everywhere else is fine, temperature of the hot water is not too hot, when using the shower the mixer is dead central, so pressure of hot and cold is the same. Most people would probably say the pressure is OK, but I want it to be VERY powerful, as it was. My plumber has come up with a suggestion, but its expensive (£500)
I have had an idea, it may be unorthodox, but I think it may work. I still have the old hot water cylinder and cold water tank. If I was to set up a separate system for the shower, mains feed into cold tank, then tank feed into cylinder, then both feeding shower via the original booster pump, could this old hot water cylinder be heated by having the water heating circuit from the boiler heating both cylinders, going through the new cylinder, into the old then back to the boiler. Both cylinder are indirect.
I have had an idea, it may be unorthodox, but I think it may work. I still have the old hot water cylinder and cold water tank. If I was to set up a separate system for the shower, mains feed into cold tank, then tank feed into cylinder, then both feeding shower via the original booster pump, could this old hot water cylinder be heated by having the water heating circuit from the boiler heating both cylinders, going through the new cylinder, into the old then back to the boiler. Both cylinder are indirect.
Unvented cylinder runs at 3 bar or 43.5 psi.
What pressure did you get from your shower pump?
What pressure did you get from your shower pump?
You cant fit your old cylinder elsewhere unless it is part L compliant. If its not insulated then it cant be used at all. If insulation is green or yellow it must be brought up to minimum compliance by fitting extra jacket. If its blue then it complies.
If your plumber fits the balancing tee in between the combination valve and the expansion core unit and fits an isolation valve then as far as I am aware you may carry on from there and run a new balanced cold supply to the shower.
Most shower pumps run at 3 bar or less so unless yours was higher than this maybe theres some crap in the filter to your shower or a fault with the shower itself.
Pipe sizing of mains to an unvented cyl is important and its generally recommended to be 22mm and must give 20 litres/min at the outlet to function properly
If your plumber fits the balancing tee in between the combination valve and the expansion core unit and fits an isolation valve then as far as I am aware you may carry on from there and run a new balanced cold supply to the shower.
Most shower pumps run at 3 bar or less so unless yours was higher than this maybe theres some crap in the filter to your shower or a fault with the shower itself.
Pipe sizing of mains to an unvented cyl is important and its generally recommended to be 22mm and must give 20 litres/min at the outlet to function properly
Cylinder is only 3 years old, so is blue insulation. The pump runs at up to 25 litres/minute and is 1/2 KW,( can't find a pressure rating on it)
How is the shower working now for you not to be happy with it ???
Is the pump still in line?
Where is it connected into the existing system?
Was it explained to you beforehand that the shower would not or might not work after the cylinder was fitted?
What does your plumber propose to do as a way round it that costs £500?
Please answer my question about the 'Benchmark booklet' and local authority being informed as the latter at least is a legal requirement.
I'm not out to drag the guy over the coals or get him into trouble but I do suspect that at least he's had difficulties , dropped a b@ll@ck on the price or is working out of his depth and I confess that I have done all of these in the past. I am here only to try and find out what is wrong of my own volition but to do this I need as much info as possible.
Just spotted this bit and its a no no .
You can still duplicate the cylinders but would have to have them zoned off accordingly to achieve boiler interlock.
Doing it your way; using an immersion heater would be a better option than connecting to the boiler 'initial cost wise' and could be a bonus if your boiler does happen to break down I do feel that the final cost of your idea could be more than you think.
Running a balanced supply feed for the shower as its supposed to be is still the best in my book as you could also get an immersion heater fitted to the unvented cylinder
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
