Accumulator

[rikakka]

Hi everyone,

 

Looking for some help/advice with a water accumulator at my brother's new house.

 

He has a problem when more than one tap is open the amount of water in the kitchen is poor.

 

We had a look around the system and found two 100l accumulators in the attic isolated. So we put them on but nothing seems to have changed. I had a look online and have tried to change the pre charge on them but not sure what it should be set at really.

 

The system looks like it's 

 

Mains

Stopcock

22mm pipe

Check valve

Prv set to 3bar

2 accumulators 

Then 22mm to the combi boiler where it Tees off to the boiler and the cold water system all 15mm 

And then the hot system is all 15mm

 

The static pressure is around 3bar according the the pressure gauge before the prv. The dynamic pressure looks around 2.5bar according to a gauge after the accumulator and the system provided about 12lpm with one outlet open.

 

Any help with setting the accumulators would be great.

 

Thanks 

Richard 

 

 

 

[Temp]

I wonder why they were isolated? I think these work a bit like large expansion vessels. See if water comes out when the precharge valve is opened.

[Temp]

Google finds.. 

 

https://pumpexpress.co.uk/explaining-cold-water-accumulators/

 

The air pressure inside an accumulator is set at 2 bar but may need adjusting so that it is between 1 – 1.5 bar below the mains pressure. The minimum this can be set to is 0.5 bar but this will require consulting the manufacturer.

 

 

[rikakka]

9 hours ago, Temp said:

I wonder why they were isolated? I think these work a bit like large expansion vessels. See if water comes out when the precharge valve is opened.

I assumed they were off due to the sale. I think the house lay empty for a while. 

 

Air comes out when I push the air valve on top.

[rikakka]

9 hours ago, Temp said:

Google finds.. 

 

https://pumpexpress.co.uk/explaining-cold-water-accumulators/

 

 

 

 

Yeah I found that information, charged it like that but it didn't seem to make much difference, certainly didn't make a difference with the kitchen tap?

[dpmiller]

Are you sure all stopcocks and isolators are fully open?

 

Is there any chance the kitchen tap is straight off the mains before the accumulator?

[fezster]

Have you checked the pre-charge with the accumulators empty, using the schrader valve? With 3 bar static, it should be 1.5 bar. You can't check it properly if the accumulator is full of water. 

[rikakka]

26 minutes ago, dpmiller said:

Are you sure all stopcocks and isolators are fully open?

 

Is there any chance the kitchen tap is straight off the mains before the accumulator?

We have followed the pipe work and there is definitely no branching off the mains before the accumulator. All the isolators are open, but maybe one is faulty?

[rikakka]

Yeah the vessels have been empty when setting the pre charge. If the accumulators are set correctly then could to be an issue with the plumbing? The whole house is 15mm and it looks like it branches first for the bathroom, next for the utility and ensuite then the kitchen looks like it's last. Maybe 15-20m away from accumulators.

[rikakka]

I found these instructions after Googling 

The code on the tank.

 

For tanks installed on mains’ pressure, the tank precharge should be set equal to the mains’ pressure.

 

But that conflicts the advice of a bar to 1.5 below and am not sure how it would fill if the vessel was set the same as the mains? Although I am no expert and probably don't fully understand the system.

 

 

Tank-Installation-and-Operation-Manual-M-MT1_EN.pdf

[fezster]

19 minutes ago, rikakka said:

We have followed the pipe work and there is definitely no branching off the mains before the accumulator. All the isolators are open, but maybe one is faulty?

 

An accumulator should be teed into the mains supplying your outlets. I.e. by definition, the mains should branch - one branch to the outlets, the other branch to the accumulator. That's how the accumulator fills and releases it's contents using the same pipe branched from the mains.

 

Have a look again, but it could indeed be a plumbing problem.

 

 

[rikakka]

9 hours ago, fezster said:

 

An accumulator should be teed into the mains supplying your outlets. I.e. by definition, the mains should branch - one branch to the outlets, the other branch to the accumulator. That's how the accumulator fills and releases it's contents using the same pipe branched from the mains.

 

Have a look again, but it could indeed be a plumbing problem.

 

 

Manage to go round to and re trace the pipe work.

 

It's definitely piped as the following

Mains

Stopcock

22mm run maybe around 4m up to the loft

Pressure gauge

Check valve

Prv

After the prv it's a teed into tank one

Then tank 2

Then into a tee one end going to the combi the other back down to supply the taps.

 

I've attached a sketch to help. 

Plumbing.pdf

[Temp]

If other taps are OK it's looking more like an issue with the pipe to the kitchen tap or the kitchen tap itself. Some taps have mesh filters that can scale up, either on the inlet to the tap or the mixer outlet.  

 

By PRV do you mean you mean a Pressure Relief Valve or a Pressure Regulating/reducing Valve? Eg does it have a tun dish and outflow pipe?

 

 

 

[fezster]

@rikakka One easy way of checking if the accumulator is holding water and working is to allow time for it to charge (see if you can hear it filling and/or watch the pressure guage on the inlet to see it slowly rise from dynamic to static pressure), then switch off your main stopcock. You should still have water from your taps until the accumulator depletes.

Edited September 27, 2021 by fezster