No.1 U.K. Professional Trade Forum, Plumbing, Gas, Electric, Tiling and Joinery Forum

I was hoping someone in the trade could give me some advice.

I recently had my oil switched over to gas. During the switch the installer advised me that I could disconnect the shower from the water tank in the attic and connect it to the mains supply. He said this would improve the pressure in the shower however the plumbing was quite old and this could also cause leaks. I didn't want to risk ending up with an expensive leak so I said to leave it connected to the tank in the attic.

Since the gas has been installed the hot water pressure in the shower is unsteady. The cold comes through fine but the hot water keeps dropping in and out, making it really difficult to shower. I've spoken to the installer and he wants to charge me further to replace the temperature mixer in the shower. I'm very wary of this, as they were abit of a nightmare during the installation, and the shower had worked totally fine before.

It's a ground floor bathroom. Previously the hot water was being stored in a copper cylinder 1 floor above the bathroom and pressure was fine. Now the boiler is trying to drag water from a tank in the attic, 2 floors above bathroom, and heat it on the hoof, hence pressure dropping in and out.

Am I on the right lines with this? And that it was inappropriate to offer to keep the attic water tank connected at all? Or am I completely barking up the wrong tree and it's likely just a coincidence that the shower needs some separate work?

Any thoughts/advice would be really appreciated!

Sounds like a combi boiler you have had installed if you have had your cylinder removed. Tanks in the loft should be dead with the shower hot fed directly from boiler and cold from mains.

what boiler is it?
turn your boiler temp control up a notch or 2 !

A Couple of things you could check would be the filters on the shower inlets, as you've had work done on the system, deposits could now be blocking the hot feed. Also need to check the working hot and cold pressures. A combi restricts the water fed through it which means your cold mains generally works at a higher pressure to the hot. Some showers dont like this and require the feeds to be balanced so a pressure reducer on the cold could also rectify the problem. I would first confirm the cold tank situation though, I may have read it wrong but it sounds like you have a combi fed from the tank in the loft because you didn't want to risk a leak caused by the increase in pressure from switching to mains, is that correct?

(Please ignore - still figuring out how to use forum )

SimonG wrote: ↑

February 24th, 2020, 6:30 pm

Sounds like a combi boiler you have had installed if you have had your cylinder removed. Tanks in the loft should be dead with the shower hot fed directly from boiler and cold from mains.

I do know the set up I've been left with isn't the standard set up that you would expect. But do you think it would cause any issues with the pressure?

Craig0787 wrote: ↑

February 25th, 2020, 1:47 pm

A Couple of things you could check would be the filters on the shower inlets, as you've had work done on the system, deposits could now be blocking the hot feed. Also need to check the working hot and cold pressures. A combi restricts the water fed through it which means your cold mains generally works at a higher pressure to the hot. Some showers dont like this and require the feeds to be balanced so a pressure reducer on the cold could also rectify the problem. I would first confirm the cold tank situation though, I may have read it wrong but it sounds like you have a combi fed from the tank in the loft because you didn't want to risk a leak caused by the increase in pressure from switching to mains, is that correct?

Thanks so much for your reply. Yes, you're spot on about the combi being fed from the tank in the loft. Tbf to the installer he did mention something about a blocked filter. Do you think it's fair enough in this case for him to charge me further to replace the temp mixer in the shower and to pay the seperate call out charge for this? From reading your post, it sounds like you don't seem to think my set up with the tank in the loft should be causing any issues with the pressure.

REDSAW wrote: ↑

February 24th, 2020, 8:26 pm

what boiler is it?
turn your boiler temp control up a notch or 2 !

Well - I've tried turning it down low so no harm in giving it a go the other way!

Markhillstown wrote: ↑

February 26th, 2020, 12:28 am

Craig0787 wrote: ↑

February 25th, 2020, 1:47 pm

A Couple of things you could check would be the filters on the shower inlets, as you've had work done on the system, deposits could now be blocking the hot feed. Also need to check the working hot and cold pressures. A combi restricts the water fed through it which means your cold mains generally works at a higher pressure to the hot. Some showers dont like this and require the feeds to be balanced so a pressure reducer on the cold could also rectify the problem. I would first confirm the cold tank situation though, I may have read it wrong but it sounds like you have a combi fed from the tank in the loft because you didn't want to risk a leak caused by the increase in pressure from switching to mains, is that correct?

Thanks so much for your reply. Yes, you're spot on about the combi being fed from the tank in the loft. Tbf to the installer he did mention something about a blocked filter. Do you think it's fair enough in this case for him to charge me further to replace the temp mixer in the shower and to pay the seperate call out charge for this? From reading your post, it sounds like you don't seem to think my set up with the tank in the loft should be causing any issues with the pressure.

Sorry for the late reply, I've been that busy lately I just havent had 5 mins to check the forum. I personally dont think the problem is with your shower. Now you've confirmed the combi is fed from a tank I would be saying that is where the problem lies. Combis are not designed to work from gravity fed systems, not on the hot side anyway. I would look at correcting this and either mains feeding the combi or running it off a pump.

still need the boiler make and model as i doubt it conforms to m.i's