Poor shower water pressure

[ChrisD.]

We have two showers, en suite (no bath) and the main bathroom (bath). Both are run of the water mains and are heated by a 40 kW combi boiler. If we run one of the showers individually the pressure is pretty low, enough to have a shower with but enough to annoy her indoors as it takes her ages to rinse her hair. If you run the other shower at the same time, flush the toilet, use a tap etc. the pressure suffers and temperature stops being stable. The bath and all taps have brilliant pressure (hot and cold).

We had a similar setup in our last house with the exception that the en suite shower was electric. The bath however was pretty poor in comparison but the shower was amazing.

The house was built in 2017 so pretty modern. My (future) brother in law thinks the issue might be that the bath has been fitted with 22mm plumbing but it'll be 15mm going to the shower. I know nothing about plumbing and what might be the issue. Changing the plumbing behind the shower is something we'd want to avoid as it's all tiled in.

Any ideas or things I can try? I've had two different plumbers round and haven't had either of them come back with quotes so I'm guessing they're reluctant to look into it properly.

 

[Peerzy]

Without changing the pipework (likely to be in the walls for the shower) you'll need to get a pump installed. A fairly routine and simple job and they can often sit in the loft. Pump would probably be about £250 and then a small amount of labour (£100-£200) to fit and test is what I'd expect.

We had poor pressure in most of the upstairs bathrooms (sinks, baths and showers) so had a 3bar pump (£350ish) fitted to provide for all of these and the difference is amazing, the power on the hosed part of the shower now pushes it backwards in your hand when previously it was nothing more than a dribble.

The other option is to investigate pipework, look for blockages, replace bits but this would normally mean going into the walls, under floors etc....

 

[ci_newman]

Without changing the pipework (likely to be in the walls for the shower) you'll need to get a pump installed. A fairly routine and simple job and they can often sit in the loft. Pump would probably be about £250 and then a small amount of labour (£100-£200) to fit and test is what I'd expect.

We had poor pressure in most of the upstairs bathrooms (sinks, baths and showers) so had a 3bar pump (£350ish) fitted to provide for all of these and the difference is amazing, the power on the hosed part of the shower now pushes it backwards in your hand when previously it was nothing more than a dribble.

The other option is to investigate pipework, look for blockages, replace bits but this would normally mean going into the walls, under floors etc....

Pumps are an absolute no-go when you have a combi boiler like the OP.

OP - do the showers have thermostatic mixers? If so, does the pressure go up as you either make the water colder or hotter? (that will tell you whether hot or cold has got the low water pressure).

 

[ChrisD.]

Pumps are an absolute no-go when you have a combi boiler like the OP.

OP - do the showers have thermostatic mixers? If so, does the pressure go up as you either make the water colder or hotter? (that will tell you whether hot or cold has got the low water pressure).

I’ve no idea what one of those is however the pressure remains the same regardless of the temperature. Not unlike my older electric shower which lost pressure as you turned the temperature up.

 

[happy_2008]

Can't really use pumps with Combi.

 

[radderfire]

A suggestion for you to investigate - Electric showers are cheap and they have inbuilt pumps, and easy to install, so you could consider installing one, you'll just have to pay for the additional electricity cost. I think this has the possibility to improve flow, but you'd have to ask an expert, as I don't know if it would work if you have narrow piping.

 

[Peerzy]

Ah - missed the bit about the combi boiler. Yeah, no pump for that unfortunately.

 

[Countcussy]

We have two showers, en suite (no bath) and the main bathroom (bath). Both are run of the water mains and are heated by a 40 kW combi boiler. If we run one of the showers individually the pressure is pretty low, enough to have a shower with but enough to annoy her indoors as it takes her ages to rinse her hair. If you run the other shower at the same time, flush the toilet, use a tap etc. the pressure suffers and temperature stops being stable. The bath and all taps have brilliant pressure (hot and cold).

We had a similar setup in our last house with the exception that the en suite shower was electric. The bath however was pretty poor in comparison but the shower was amazing.

The house was built in 2017 so pretty modern. My (future) brother in law thinks the issue might be that the bath has been fitted with 22mm plumbing but it'll be 15mm going to the shower. I know nothing about plumbing and what might be the issue. Changing the plumbing behind the shower is something we'd want to avoid as it's all tiled in.

Any ideas or things I can try? I've had two different plumbers round and haven't had either of them come back with quotes so I'm guessing they're reluctant to look into it properly.

Now, without getting too technical, flow and pressure are relative, but different.
Its quite typical for a shower to be on 15mm, especially a thermostatic, as it has 2 feeds, hot and cold. Unless you have really good flow but really poor pressure, Increasing the pipe size will have little effect, as each 15mm pipe is more than enough to carry the required flow for hot and cold to a shower head.
What does not make sense, is that the bath tap pressure seems ok. The bath tap will be on 22mm, to allow more flow, otherwise your bath would take longer to fill up.
On a shower, The holes in the shower head will determine how much water can actually come out. And the pressure will determine how quickly it comes out, based on the flow.
Has this issue just started? Or has it always been this way? What temp is the shower mixer set at?
Being on mains, you are governed by the pressure entering the property. This will fluctuate during the day, sometime quite wildly depending on the surrounding properties. Add into the fact that more people are at home, and it can vary massively.
Shower valves can get choked up with scale over time, which will reduce flow, which can sometimes be perceived as a loss of pressure.

I have a system boiler and cylinder, so I cannot comment on the combi. What's the max flow rate through a 40kw combi? Edit: Just googled it, 16.4 l/min. Coupled with a cold supply, more than enough for a decent shower.

 

[ChrisD.]

Has this issue just started? Or has it always been this way?

We bought the house less than two weeks ago and it's been like it since we moved in, unsure what it was like before. I've also been told about filters on the hot/cold inputs of the shower unit itself, is it worth turning off the water supply, letting it drain and having a look at these? Or could it be the shower unit itself (it's an Ideal)?

 

[Countcussy]

Ah, ok.
The filters are worth a check.
It could be the mixer, but they are normally pretty robust.
One thing you could do is take the shower head off and just run the hose. Do things improve? By which I mean does plenty of water come out? Have the sellers fitted ECO shower heads designed to use less water?
You have a lack of flow, and we need to isolate why.

 

[ChrisD.]

One thing you could do is take the shower head off and just run the hose. Do things improve?

Ha, not sure why I didn't think to try that. The pressure is pretty much as strong as the bath so I think it might be the head. Any recommendations or just find a well reviewed one on Amazon?

 

[peterwalkley]

Ha, not sure why I didn't think to try that. The pressure is pretty much as strong as the bath so I think it might be the head. Any recommendations or just find a well reviewed one on Amazon?

Some have a flexible material on the head you can rub a thumb over (firmly !) to unclog the jets - so try that if you've not done so already. Failing that, they're pretty standard and cheap. Last time I had to do the same it was a trip to B&Q and I just bought the first one that looked pretty much like the one being replaced.

 

[413x]

Jumping on this thread.. So with no combi boiler can just get a pump fitted and job done? The water pressure on cold (hot is a tank)is absolutely terrible.

 

[Peerzy]

Jumping on this thread.. So with no combi boiler can just get a pump fitted and job done? The water pressure on cold (hot is a tank)is absolutely terrible.

We had a 3bar pump fitted as our cold was rubbish throughout the whole house and hot upstairs was pants. It does everything apart from the cold tap in the kitchen and utility room and has made a massive difference. I can't turn a few of the taps on full now as they'll splash water everywhere.

This is with a fairly newly fitted system boiler system.

 

[413x]

We had a 3bar pump fitted as our cold was rubbish throughout the whole house and hot upstairs was pants. It does everything apart from the cold tap in the kitchen and utility room and has made a massive difference. I can't turn a few of the taps on full now as they'll splash water everywhere.

This is with a fairly newly fitted system boiler system.

What was the total cost of fitting/pump itself?

Probably looking at just cold here as hot seems fine. Its certainly fine in Bath. But cold just dribbles out.

 

[Countcussy]

Ha, not sure why I didn't think to try that. The pressure is pretty much as strong as the bath so I think it might be the head. Any recommendations or just find a well reviewed one on Amazon?

Personal preference, but some are much better than others. My 2 showers have the Triton Lara head. Easy to clean and 3 nice spray patterns. Can be had for around £14

 

[Psycho Sonny]

I had a pump fitted but I think the guy didn't install it at the right location as it's made zero difference.

I have a system boiler, hot water tank in a cupboard upstairs and then 2 tanks in the loft.

My cold water pressure is fantastic, it's hot that is the issue. Brand new mixers in both showers.

I got a pump installed where the en suite is so right behind the mixer in the shower. It's made pretty much zero difference as I believe the pump should have been installed closer to the source of water rather than the exit.

Should the pump be installed next to the tank or the shower?

The guy who did the job is a bit of a spanner. He left one of the new mixers loose and water was leaking until he came back.

 

[Mason-]

@ChrisD. It might be a flow restricter in the shower head rather than the head being gummed up. It should be just inside the shower head where it screws in. Some are a pain to get out.

like this:
https://youtu.be/vE87Vq-Xefc

 

[peterwalkley]

Jumping on this thread.. So with no combi boiler can just get a pump fitted and job done? The water pressure on cold (hot is a tank)is absolutely terrible.

That's what we used to have before switching from a system boiler to combi a few weeks ago. Pump was in the same cupboard as the hot water cylinder and prior to getting it installed the showers were useless. Cold water pressure fine, hot was rubbish.

One "gotcha" with ours was that the pump was plumbed in so that all taps would activate it, instead of just the showers. It ended up that way as doing it for just the showers would have been a much bigger job routing new pipes or taking up flooring. What we used to do was only switch the pump on for showers and then off the rest of the time.

You should talk to a competent plumber who can look at your pipes .... It might be simple and fairly easy, it might be a complete pain.

 

[413x]

That's what we used to have before switching from a system boiler to combi a few weeks ago. Pump was in the same cupboard as the hot water cylinder and prior to getting it installed the showers were useless. Cold water pressure fine, hot was rubbish.

One "gotcha" with ours was that the pump was plumbed in so that all taps would activate it, instead of just the showers. It ended up that way as doing it for just the showers would have been a much bigger job routing new pipes or taking up flooring. What we used to do was only switch the pump on for showers and then off the rest of the time.

You should talk to a competent plumber who can look at your pipes .... It might be simple and fairly easy, it might be a complete pain.

Would also mean could get rid of the electric power shower. As I guess that's mainly been installed by previous owners for water pressure issues?