[Fellsteruk]

Hey,

I'm after some advice with regards to a bit of a mess my parents have been left in after getting a new bathroom. I've got a proper plumber coming out but it wont be until end of next week and just curious if anyone can help signpost possible cause, maybe a quick fix.

Background
They live in a 1960's 2up/2down house and before the new bathroom water pressure wasn't magic but useable and in the bathroom they had an electric shower. I don't know exactly what type of system they have but i think its a regular boiler which does the hot water and heating but also have a vented cylinder and water feeder tank in a cupboard above the cylinder.

The issue
New bathroom in, they replaced the electric shower with one powered from the hot/cold mains supply, no surprise to me the thing didn't work just dribbled hot water, they fitted a salamander pump for the shower and although it does give more pressure it doesn't always kick on unless you lower the shower wand at floor level. My GCSE physics tells me that maybe the pump isn't picking up the drop in pressure, then when the wand is on floor level, much lower than the feeder tank the syphon effect / pressure difference being greater the pump kicks in also the pump is noisy as hell so I'm convinced that isn't fitted correctly or has an air lock as my pond pump isn't that loud and it's doing 8,000lph but I digress.

The other issue is that the hot water to the sink is a very slow trickle so much so i was convinced they had left a value half open or something but no all open. I checked the flow rate and its about 2litres/min which is shocking that they find this acceptable and whilst i didn't measure before is far less than the old bathroom.

I actually helped my dad rip the old one out to save money on the install and i noticed that both the old sink and bath were feed by a 22mm copper pipe which just to the bottom of each tap stepped down to 15mm im guessing to help maintain some head pressure?

I had a look at what they had done and they seem to have replaced about 7ft of the 22mm pipe with 15mm polly pipe, ive no issue with the polly pipe but im wondering if the fact they have remove so much of the 22mm pipe that its reduced the head pressure as the hot water to the tap now has to travel about 10ft after the step down when it was only 3ft before.

Im no plumber, i know enough to cause trouble but i feel like they have made some pretty basic I've paid and getting a proper plumber to come out next week im just curious if anyone is in the trade and can, from what I've shared put 2 and 2 together to help me understand what has gone wrong.

The cherry on the cake when complaining about this was "you need a combi boiler, this isn't that bad"... I wont repeat my response, sadly i didn't pick the installer and actually wanted my parents to use the bathroom fitters id used myself previous who were great but they are adults, have to make their own decisions what can you do

All comments welcome.

[Sooty25]

I've got a salamander pump and yes it is as noisy as hell! Try rubber mounting it to try and reduce the resonation through the house. Also check they have plumbed it in with flexi's not direct to poly pipe.

You need to figure out the flow rate problems, pump should start as soon as you turn the mixer tap on.

[Fellsteruk]

Thanks Sooty, i'll check if it had the feet on and how the plumped it in i don't recall 100% but pretty sure its direct to hard pipes

Spent a little more time on the Salamander website and i think the issue with the showing not kicking in or only when wand is on the floor is because with what they have installed there is no positive head, in fact im guessing it must be negative as there is less than 600mm space from feeder to shower:

"If you cannot measure the water flow rate, then you can check if the system is suitable for a positive head pump if there is more than 600mm between the base of the cold-water storage tank and the highest point in the system after the pump. For example, the illustration to the right shows a shower with pipework below the dotted line indicating the 600mm point."

Looks like they should have fitted a negative/universal pump rather than the positive one they installed, i guess the other option is to increase the height of the feeder tank... wait till i break the news to my parents.

[T6Harvard]

Check their credentials and report to any trade body they claim membership of. Any paperwork? Check claims they make on there / any website and report to Consumer Direct if false.

I share your despair. Why DO relatives ignore the golden rule to find a trader by personal recommendation rather than a glossy ad, or God forbid, a leaflet through the door?! Oh but they seemed so nice, looked smart, had a lovely brochure, proper ID and everything..... agggghhh.

Sorry, can't help with the plumbing q. You have done as much as I would have.

[Bill McCarthy]

Measure the “head of water” - the vertical distance between the cold water header tank and the hot water cylinder. In addition - what is the vertical distance between the shower rose in its holder and that cold water header tank. Modern taps of the hot/cold single unit type, if that is what they’ve fitted, just have an 8mm connection to them. Is the cold water at mains pressure ? For a shower fed from a hot water cylinder, the cold should come from the same header tank in order to be at equal pressures to the shower rose.
It sounds like the head of water between the shower rose and cold water header tank is minimal.

[johnm]

If the header tank is in the same cupboard as the hot water cylinder then you have your answer I think. It's a set up that was fairly common in the 1960s and the cylinder and tank are close coupled and the system is open vented.

The symptoms suggest lack of head and possible air locks and I suspect that the only long term solution is to replace the cylinder and tank and have the tank on a stand in the loft. You might get away with a suitable shower pump and the source for both hot and cold needs to be the tank. There's some useful info here

I'd be cautious about installing a combi boiler or pressurised closed system as the pipework is not likely to be sufficiently leak proof and the tiniest leak will result in a constant need to re-pressurise the boiler.

[Fellsteruk]

Thanks all

That website explains it pretty well to be fair and concludes in my mind that it’s the wrong pump, the shower rose is higher than the base of the water tank and the shower wand whilst lower isn’t much lower so clearly a negative pump is needed not a positive one like they have fitted.

Looking at the price of these pumps I’m started to maybe realise they fitted the one they did because it was cheap much cheaper than any negative I can see.

The hot water tap which is pi$$ poor isn’t connected to the pump but I’m guessing a solution could be.

Replace the pump with a 2-3bar negative pressure pump and use it to feed the shower and tap?

[rikur_]

The tap should be solvable without putting it on the pump.
Most taps on the market now are designed for a pressurised system, to the extent that you specifically need to look for one for a vented system.

[johnm]

Is the cold feed to the basin from the mains supply? If not they should be the same and if the hot is then slow it may be an airlock if the pipes are not run smoothly and secured in clips. Look for the tap on the web and see what pressure range it is designed for.

[Fellsteruk]

Cold seems to be mains supply as the cold is pretty powerful far more than hot.

Yeah I’m pretty sure the taps are for pressure system will try find the spec.

[rf3flyer]

One other thing that can cause poor flow is an upward loop. If pipework has been rerouted and if at some point the pipe goes up before it goes down, perhaps to jump over a rafter, that loop will be unbleedable and will impede flow.

[lobstaboy]

I think the reduction in pipe diameter is significant. The cross section varies by the square of the radius
22mm dia is approx 360mm2 cross section
15mm dia is approx 170mm2
So the smaller pipe can pass only less than half as much. Flow rate and effective head will be reduced by half, roughly - more than enough to cause you problems if it was a bit marginal originally.

[johnm]

Normally 15mm is ample for a basin 22 mm needed for a bath

[rikur_]

I think the reduction in pipe diameter is significant. The cross section varies by the square of the radius
22mm dia is approx 360mm2 cross section
15mm dia is approx 170mm2
So the smaller pipe can pass only less than half as much. Flow rate and effective head will be reduced by half, roughly - more than enough to cause you problems if it was a bit marginal originally.

Wider diameter = longer until hot water reaches the tap. Not necessarily a problem if you are near the tank in the bathroom, but can be for other rooms. 15mm is normal for basin taps, even with a vented system .... as @lobstaboy says it's all contributing to the issue - but the right tap on 15mm should be fine assuming no other issues.

[Paul_Sengupta]