Low hot water pressure

[tntcoder]

Hi,

Recently moved into a house and un/luckily one of the only things wrong is low hot water pressure. One of the two showers is basically not usable and the other is poor at best. Both standard mixer showers.

It appears to be a mavity fed system as follows, all in a stack above each other:

Loft: Cold water tub/tank
Second flood: Hot water tank
Ground floor: Gas Boiler - pressure on this is in the green, just under 1.0 bar

It's on a two-zone CH setup as well.

There does not appear to be any pump in the system, every hot tap/shower is terrible except the bath hot tap - interesting that's fine but nothing else is. All other taps and showers are really poor.

The kitchen hot tap takes ~30 seconds to get warm and is about 30% pressure of the cold, despite being lowest in the system and closed to the boiler.

How would you go about diagnosing this? I've double checked all the valves are fully open but my first step is to get the boiler serviced and hope they can do some magic.

Could it be that adding a pump to the hot will fix it? Or could it be something like lime scale build up in the pipes. Am I best just to book a plumber out to assess it?

This is the stuff under the boiler:



Thanks

 

[wonko]

I'd expect the hot water is mavity fed, with the water pressure determined by the height of the header tank in the loft. If the bath has larger diameter pipe it would explain the better flow than other taps, especially if it's close to the hot cylinder.
When i had an extension built I replaced my hot water cylinder with a Megaflow to get mains pressure hot water - might be worth looking at but not cheap.
p.s. you might want to check that your header tank is covered and hasn't got anything that's died in there...

 

[tntcoder]

I'd expect the hot water is mavity fed, with the water pressure determined by the height of the header tank in the loft. If the bath has larger diameter pipe it would explain the better flow than other taps, especially if it's close to the hot cylinder.
When i had an extension built I replaced my hot water cylinder with a Megaflow to get mains pressure hot water - might be worth looking at but not cheap.
p.s. you might want to check that your header tank is covered and hasn't got anything that's died in there...

Thanks a lot. If it is down to small pipes, is that something a pump can fix?

I like the look of the megaflo, and will definitely consider that longer term. I assume older/smaller pipes can take the pressure? I was hopefully there might be a cheaper short term option.

 

[Psycho Sonny]

Thanks a lot. If it is down to small pipes, is that something a pump can fix?

I like the look of the megaflo, and will definitely consider that longer term. I assume older/smaller pipes can take the pressure? I was hopefully there might be a cheaper short term option.

Get a pump I had the same issue bought a pump the water comes out like Niagara Falls now.

The more you spend the quieter they are. I spent around £250 on mine but they go up to around £500 and start at around £80.

 

[Dangerous Dave]

Can you post a photo of your hot water tank ? It could be an unvented water cylinder which you can’t run a pump off.

 

[Quinnaay]

Moved in to a house and have the EXACT same as op bath water is rapid and hot shower is poor flow and down stairs tap takes ages for hot water.

 

[Jamesyboyjim]

Had the same issue when we bought our house. Shower was basically useless. There actually was a pump in use too which we discovered when we ripped the bathroom out but it was a cheap and didn't make much difference so if you're going the pump route don't go cheap! We had our system replaced with a condensing combi so now pressure is mains throughout the house which is lovely. Just means having to be careful if someone's in the shower.

 

[Pho]

I recently fitted a pump to boost the pressure of one of the taps from a tank fed system, I ended up going with one from Salamander as they seemed to get good reviews. If you give them a call they are actually ultra helpful at recommending the pump you need.

I ended up with a CT Force 30 SU which is suitable for showers, I bought it off eBay for about £150 in the end.

 

[Sin_Chase]

I have the same issue except bathroom feed for shower / bath has a pump to boost the pressure.

Kitchen is so bad the mixer doesn't work, all hot or all cold.

Considering a whole house pump but will need to investigate the cylinder suitability.

 

[tntcoder]

Thanks all, good to here this is a common problem!

Can the Salemander CT pumps sit on the exit feed from the hot water tank and cover the whole house? Or do they have to be fitted inline with a specific feed?

This is my hot tank, not sure if it's vented or not?

 

[Sin_Chase]

Salamander have whole house products, their website has comprehensive installation rules / instructions which will give you a good idea of of suitability.

One of the main considerations is a suitable vent and an Essex flange to prevent cavitation in the pump from air ingress.

 

[Pho]

Thanks all, good to here this is a common problem!

Can the Salemander CT pumps sit on the exit feed from the hot water tank and cover the whole house? Or do they have to be fitted inline with a specific feed?

This is my hot tank, not sure if it's vented or not?

Caveat: I'm not a plumber, this may be wrong!

It doesn't seem to have a problem feeding the whole house for me, but I only have ~3 hot water taps.

Assuming the copper pipe going upwards in the first photo is your outlet then that's pretty much the same as my set-up. The pipe should tee off - one part of the tee will go back to your header tank (the vent pipe) and the other half down to feed your water pipes that go to the taps etc. I placed my pump inline on the down pipe that goes to feed the water pipes, this was how they recommended to install it.

Normally I would have soldered the new pipework but I actually ended up using 22mm speedfit elbows. Mostly because it was a complete nightmare to get a propane torch to the back of the airing cupboard to solder it properly and it's easier to twist and adjust the plastic fittings to get everything lined up. As it happens this was the best decision I made because despite shutting the stop-tap on the vent pipe all the way off it was still dribbling a fair amount once I cut the pipe. There's no way I would have been able to solder it when it was wet!

I can't remember the exact reason why now but they recommended the CT Force 20/30 SU for me because it was suitable for negative head - which is where you have the cold water tank / pump sat below the height of some of the taps in your system. My cold water tank is in the loft, the pump sits on the floor of the airing cupboard (1st floor) and the taps in the bathroom are about ~1m higher than it but they still suggested I go for a negative head pump.

They also told me that for the 20/30 SU pumps whilst recommended you don't need to install a flange unlike say the one in the video below. This makes it a lot easier.

This is a slightly different model of pump but it's a great video (from a great channel) on how to install one of these pumps: