Problem with flow rate upstairs only

[blueplanet]

Hi Could I ask for some help with a water flow rate problem.

I have good mains water pressure on the ground floor. There is no tank in the loft but an unvented cylinder in the upstairs airing cupboard. A gas heat only boiler.

Upstairs I have two en suite rooms. One with a shower and one with a bath. Basin sinks in both rooms.

The cold flow rate is very poor in both rooms whether shower/bath/basin taps. Sometimes nothing comes out. The hot is good for about 30 seconds and then it drops to almost nothing in the shower/bath and basin taps. You cannot have a shower or bath at the current rate.

I've checked all the stop cocks and they are all fully open. There is a pressure top up in the airing cupboard and its at 1.5 bar.

As the flow rate is good downstairs and the system runs off the mains it seems the problem is inside the house. Anyone have any suggestions on what I else I should check or suggestions for the problem? Thanks.

 

[snowhead]

Has it always been this bad or has it suddenly changed or gradually changed?
Has there been any work done prior to the pressure issue?

 

[blueplanet]

Has it always been this bad or has it suddenly changed or gradually changed?
Has there been any work done prior to the pressure issue?

It used to be excellent. Its got worse over time. The downstairs is excellent so clearly the mains pressure coming in is good. The hot water is good for about 30 seconds (thus probably no blockage) and then it drops to a trickle. The cold is poor but used to be excellent.

In 2017, the unvented cylinder was changed from a "Something" Tribune to Joule. Flow was good. Then in 2021 the Joule was replaced by Fabdec unvented solar cylinder due to a solar thermal panel being placed on the roof. The flow was OK but not great. It gradually got worse to very disappointing in mid 2023. In October 2023 the solar thermal panel was removed. The flow is virtually non existent now.

 

[John.g]

Has this unvented cylinder got a external expansion vessel (usually white) or has it a internal bubble, yours may be something like this with aerated water going to the cylinder, wonder is this, if installed, is having some adverse effect, you arn't getting air out of the hot tap I hope. Did any G3 plumber take any pressure readings off it or inspect it?.

 

[blueplanet]

Yes, there is white expansion vessel. I have attached a photograph.

There does not seem to be air in the hot water tap. It stops running to a trickle but I do not think there is air. In October 2023 the solar thermal panel was removed but the pipes to the cylinder are still there - its just the solar part for pumping the solar glycol is off. However, the flow was disappointing in mid 2023.

No G3 qualified plumber has inspected it in recent months but that maybe the next step....

 

[John.g]

What is the chrome coloured item below the 3bar PRV on the cold mains?. Can you see where the white EV is teed into the system?

 

[ShaunCorbs]

What is the chrome coloured item below the 3bar PRV on the cold mains?. Can you see where the white EV is teed into the system?

Scale reducer

 

[blueplanet]

Scale reducer

Yes, the SESI scale inhibitor. I will report back on the white EV.

 

[ShaunCorbs]

Yes, the SESI scale inhibitor. I will report back on the white EV.

22mm to 15mm tee

Is the hot water ok in the problem zones ?

 

[blueplanet]

The white EV feeds into the same pipe as the scale inhibitor, balance and other value. It runs from the EV to same pipe but above the aforementioned valves. You can see it (15mm) going into the pipe - the pipe going in is roughly level with the white power switch (with black cable coming out underneath switch). That 22mm pipe (the one with scale inhibitor etc) then runs to the bottom of the cylinder.

The hot water is fine for about 30 seconds and then stops running.

 

[John.g]

Is that a pressure relief valve (set to 6bar?) above the 3 bar PRV? if so, then the mains flow should be upwards through the scale inhibitor, through the PRV and then back down to the cylinder?, there seems to be a blanked balanced cold port on the PRV which isn't used, where is the cold mains to the shower&tap mixers reduced in pressure?.

 

[blueplanet]

Is that a pressure relief valve (set to 6bar?) above the 3 bar PRV? if so, then the mains flow should be upwards through the scale inhibitor, through the PRV and then back down to the cylinder?, there seems to be a blanked balanced cold port on the PRV which isn't used, where is the cold mains to the shower&tap mixers reduced in pressure?.

There is a 8 bar valve above the 3 bar one (see attached) I think the 3 bar valve is a balancing valve. Yes the water flows upwards through the scale inhibitor, through the balancing valve and then into the cylinder. The cold water out of the tap upstairs is very poor too - worse than the hot.

I was thinking for the cold water - maybe the scale inhibitor is blocked. For the hot water perhaps a problem with the cylinder or a valve on the cylinder.

 

[John.g]

The (balanced) cold water seems to be (properly) taken off the 3 bar PRV so if the scale inhibitor is blocked or the PRV is defective or has a filter that's blocked then both hot & cold will be equally affected. Get those looked at.

 

[ShaunCorbs]

Does downstairs hot have the same problem?

 

[blueplanet]

Does downstairs hot have the same problem?

Downstairs the hot works fine but I will double check tonight when I get home.

 

[blueplanet]

I checked the downstairs and its seems OK. The flow starts good and then drops but not to point it is not usable. In relation to upstairs and thinking about my previous comments it cannot be a blockage to the scale inhibitor as the flow starts good but then drops. If there was a blockage it would be consistently poor.

 

[John.g]

After the cylinder is reheated then the pressure in the EV will be ~ 3.8bar and when you open a hot tap then you will get ~ 3 to 4L of water (depending on cylinder&EV volume) before the pressure in the EV returns to 3.0 bar so if the initial flow only lasts for ~ 30 secs or so then this may account for this. Its strange though that the d/stairs hot flow is OK as all the HW comes from the unvented cylinder,
If all the u/stairs HW is via mixers then there might be a problem with one of them, is the d/stairs HW tap not from a mixer?.

 

[ShaunCorbs]

Sounds like a filter is blocked / restricted need a g3 engineer

 

[John.g]

Is there a reason for installing all unvented cylinders without a pressure gauge as standard?.

 

[blueplanet]

Sounds like a filter is blocked / restricted need a g3 engineer

I checked the downstairs again today. The hot does stop after a while. The cold is good - as off the mains.

So reviewing everything again. Flow into the house is good and downstairs cold is good. Upstairs cold is poor. The hot is good for 20 seconds and then stops. The cold feed upstairs goes into the cylinder.

I suspect, as you say, the filter or something else (balancing valve) is blocked/restricted. That probably restricts the flow rate into the cylinder. Hot is good for first 20 seconds as there is sufficient water (and thus pressure) in the cylinder to allow the flow to seem good for first 20 second but then the cylinder may not be filling up with cold (due to the poor flow) quickly enough to keep it flowing.

I've tried to find a g3 engineer but no luck so far. I will update again in due course.