HW tank pipe work

[tandal]

Hi All.

I have trouble with the hot water pressure in our house. I have read through the posts on the forums and used it to trouble shoot first. I have:

- Checked bled the valve attached to the tank - OK
- Checked the header tank in the loft is 3/4 full and functioning - OK
- Run all the hot taps/cold taps to try and release any air blocks like that.

The basic setup is:
First floor bathroom with hw tank in airing cupboard outside the bathroom. The main water tank is in the loft almost directly above (about 2.75m). There is two pipes going in the bottom of the hw tank (feeds I assume) and a hot one exiting the top.

Here is my question:

This hot pipe branches off in two directions. One going to the bathroom and then eventually down to the kitchen and the other branch goes back into the loft and exits above the main water tank up there.

Is this correct? It seems that it shouldn't be running out into open air (not a sealed unit so no pressure).

Any thoughts?

Thanks a lot.

 

[denso13]

That sounds ok, the vent pipe going to the cistern in the loft is normal.

Has the pressure always been bad or has it got worse over time?

 

[BingoBongo]

is it bad at all outlets?

has the cyl been drained at all?

has the hw been turned off and the gatevalve not fully opened?snapped in off position?

 

[tandal]

Thanks for the replies.

denso13:
I have since found diagrams on the net and it is indeed a vent pipe. We have only moved in a few months ago and yes, the pressure was always bad.

BingoBongo:
It is not great at any outlets. We had the same set-up in our previous property and the water pressure in the hot taps was much better. Me next step was going to drain the cylinder and check for any sediment/scale build-up.

Could this build-up prevent the cold water feed from pushing the hot water out the top?

I cant say about the gatevalve.

Thanks a lot.

T

 

[tandal]

Still struggling with this. We have removed a lot of the cold water feed pipework and put bent pipes in and soldered the joints instead of all the compression joints and corners that was there. Thought this might encourage the flow and push hot water out a bit stronger. Unfortunately this didn't work.

Any ideas what to do next? Would replacing the tank help at all or is there something else I can do?

Thanks again

 

[kidgreen61]

Firstly, check for any obstruction in the outlet pipe of the cold water storage tank, then see if the gate valve is opening fully on the cold feed pipe. You may have to remove the valve to see if it is opening fully.

 

[tandal]

No obstruction at the cold water outlet and the pipework from there down to the hot water cylinder is new with smooth bends instead of all the corner joints that was on there. Replaced the gate valve with a 22mm full bore cut off valve which opens fully.

 

[Richard C]

What type of taps are fitted; many modern units are suitable for high pressure systems only (combi boiler) & will not function at all well on a low pressure, gravity fed system.

You could have excessive lime scale build up or an obstruction in the HW pipe work itself somewhere; also, HW pipe runs should be in 22mm until at least the first major branch or further if long runs are involved; a long, horizontal 15mm pipe run can reduce gravity pressure at the tap significantly.

 

[tandal]

Hi Richard
The taps are 1/4 turn mixer taps. I am trying to find out whether they are high/low pressure.

HW pipe work. All 22mm apart from a 40cm branch going to the bath hw tap. They are new pipes so they should be clean inside.

Do you think there might eb a sediment build-up in the bottom of the hw tank preventing the cold water from flowing in freely? The tank is 6 years old.

 

[Richard C]

Low pressure bath taps are usually 22mm not 15mm so you may have the wrong taps fitted.

I doubt lime scale would build up to the level of the inlet in 6 years but there is no real way of telling unless you remove the tank connections, inspect it & do a flow test. I recently removed an old style, un-insinuated 40 year old tank in a relatively hard water area & although it was pretty well cruded up at the bottom & the c/w inlet was somewhat restricted it was still clear of debris & sediment in the bottom of the tank.

Check out the taps but if they aren’t the cause, all you can do is work your way through the system until you find the cause of the restriction.

 

[kirkgas]

one thing you could try to eliminate the type of taps is to cut into the supply where it goes up to the whb, fit a bend and alter the pipe by using a couple of bends to over the bath edge then point down, turn the hot water back on, get someone to hold the pipe over the bath, and see what happens, to refit, remove your temp pipe and fit a straight coupling where you fitted the first bend, bit of a hassle but might indicate if you are getting a decent flow and might help flush out any cr@p.
OR you could remove hot and cold washine machine hoses under kitchen sink, fit cold hose to hot valve, open both valves and check flow from hot taps, remember when you close the taps the mains pressure will be forced up into the tank, this might clear a blockage but will also back fill tank which will then overflow so you will need a second person to assist with this as well.

 

[tandal]

HI. I went home last night and took the main tap part off from the two 'footings' it rests on on the bath. Opened up the cut-off valve behind the bath and the hot water shot out of the pipe. Almost the same aas the cold water. So our pipe work and other bits improved that because it wasn't like it a while ago.

So, hot water pressure is excellent now - PROBLEM WAS THE TAPS. According to the retailer they operate well only from 1bar upwards (mine is about 0.25bar). Someting they forgot to mention when I told them I have a gravity system and would the taps work!!

Lesson learnt, problem solved. thanks to all for your input.

 

[Richard C]

PROBLEM WAS THE TAPS. According to the retailer they operate well only from 1bar upwards (mine is about 0.25bar). Someting they forgot to mention when I told them I have a gravity system and would the taps work!!

Lesson learnt, problem solved. thanks to all for your input.

& another one bites the dust