Coldwater Accumulators - 1 not filling

[Skiddaw]

Hi,

First post, just joined in the hope someone may kindly be able to help with the problem as per the thread title. I will explain the setup:

On non mains water into holding tank then fed into house, into 2 accumulators via a Mainsboost charger. Been working fine for many years. During recent cold weather the external pipes/tank froze. This happens quite often due to being in an area which has very cold weather. Once defrosted everything normally kicks back in working. This time we received an error on the mainsboost charger saying it had failed. It had indeed failed and has now been replaced. So onto the issue, following the charger replacement, only 1 of the accumulators is filling. Plumber has checked everything he thinks and ST (Stuart Turner) tech help have been very helpful but to no avail.

Having tested the diaphragm in the vessel which is not filling, there is no water coming out of the schrader valve so the presumption is it is fine. All inlet valves are open to the vessel.

There has been lots of mentions of the vessel pressure. Today the readings for the 2 vessels were 0.95 bar for the one filling and 1.2 for the other one. The suggestion was to set the pressure to be the same for both which we have done. The mains pressure reading is 1.5 bar, so am I right in thinking the differential will mean the pressure on the vessels needs to be lower?

On setting the pressure on both vessels to 0.95bar and restarting the charger the same thing happened, only 1 vessel filled. If we shut off the inlet valve to the vessel which is filling and only leave the other one open, still no water goes into it. The charge continues running until the auto 180min cutout kicks in.

I really am hoping someone can help. Is there anything else, obvious or not, which is likely? We are in a very rural area and finding plumbers who can help is proving difficult. ST do not have any technicians anywhere in the county.

Many thanks in advance.

 

[Skiddaw]

If you set the pre charge pressure to the mains pressure of 1.5bar and pump the accumulator to 2.8 bar then the (each) accumulator will accumulate 154 litres of water and will release the same in falling from 2.8 bar to 1.5 bar.
IF it requires 3 hours to charge each accumulator the the charging pump is only pumping 0.85 LPM, something certainly not right there

 

[Skiddaw]

It is not normally 3 hours, before the charger change both will fill from empty in about 15 mins. The 3 hours I mentioned was how long the charger will run before auto switching off. We only let it run after the charger had been replaced to see if both accumulators would fill, we contacted the plumber (who had left once the charger had been replaced) when it was quickly clear only one vessel was filling, they normally both fill at the same time. He said to leave it for longer to see if the other one filled, hence leaving it until the charger hit its maximum run time before shutting off.

 

[John.g]

15 minutes seems OK, = ~ 10/15 LPM. You will get a accumulated vol of 220 litres with pre charge pressure of 0.95 bar and the same released in falling to 0.95 bar but only 121 litres to 1.5 bar, still not bad.
When you say one accumulator is not filling do you mean the pressure is not rising to 2.7/2.9 bar?, is it rising at all?.

 

[Skiddaw]

15 minutes seems OK, = ~ 10/15 LPM. You will get a accumulated vol of 220 litres with pre charge pressure of 0.95 bar and the same released in falling to 0.95 bar but only 121 litres to 1.5 bar, still not bad.
When you say one accumulator is not filling do you mean the pressure is not rising to 2.7/2.9 bar?, is it rising at all?.

No water is going into one of the accumulators at all, well as much as I can ascertain it isn't, it remains hollow sounding when empty compared to the other one which doesn't, it is the way we have always known they are full. TWS (now Stuart Turner) always said it is the best way to know they are full!

 

[John.g]

Actually you said it only takes 15 mins to fill both together so the charger is pumping ~ 25 LPM.

If no pressure gauge anywhere its quite easy to see if its charging or not, just check the pressure at the air end (assuming you have a pressure gauge) it will be exactly the same as the water side.

 

[Skiddaw]

Actually you said it only takes 15 mins to fill both together so the charger is pumping ~ 25 LPM.

If no pressure gauge anywhere its quite easy to see if its charging or not, just check the pressure at the air end (assuming you have a pressure gauge) it will be exactly the same as the water side.

We see the pressure on the charger which normally gets to just below 3 bar, the mains pressure gauge also increases accordingly to normally the same, is that what you mean?

 

[John.g]

Yes, this pressure should (normally) reflect the pressure in the accumulator(s), it will only read the correct pressure for the "bad" one if the other is isolated from it, the only other reason I can think of is that the diaphragm is stuck or jammed up against the water end but the pump should then cut out almost immediately on its pressure switch, taking the air end pressure will reveal a lot.

 

[Skiddaw]

Yes, this pressure should (normally) reflect the pressure in the accumulator(s), it will only read the correct pressure for the "bad" one if the other is isolated from it, the only other reason I can think of is that the diaphragm is stuck or jammed up against the water end but the pump should then cut out almost immediately on its pressure switch, taking the air end pressure will reveal a lot.

Yes, even with my very limited knowledge, the fact the pump does not cut out has confused me. When I closed the inlet valve for the one which is filling to try to "force" the other one to fill and it didn't I expected the charger to shut off, it obviously didn't.

I am not sure what you mean by taking the air end pressure. My plan is to change the pressure on each vessel again in the morning after emptying and try again. I will update the thread once done, nothing more to do tonight other than sleep!

Thanks for everyone's help.

 

[ShaunCorbs]

It’s trying to charge your whole system to 3.5 bar or what ever the charge pump is set too hence it never got there and erred out

 

[John.g]

What I mean by checking the air end is simply taking the air pressure which you read anyway when changing air pressures, if its still at the pre charge pressure then obviously no water in the other end.

 

[Skiddaw]

Morning. Thanks again for the posts yesterday.

This morning husband drained down the system. The vessel pressure were both 1.0 bar. We only have a small bike pump so struggled to get the pressure up on either vessel, in fact could not increase it at all.

Made sure there was no air in the system (air coming out of taps) and switched everything back on. Only one vessel filled again exactly as before.

Drained the system again once switched back on ensured the isolation valve to the vessel which was filling was closed. Once again the other vessel did not fill.

Final time have drained the system again and am now currently seeing if both vessels fill, I am not expecting any difference with only one filling.

If the vessel pressure is wrong (should be higher (or lower) than the current 1.0bar) why would one tank fill with that pressure setting?

Once again sorry if stupid questions which may have been answered before.

Thanks in advance for any further assistance.

 

[John.g]

Where are you measuring the 1 bar pressure?

 

[Skiddaw]

Where are you measuring the 1 bar pressure?

The Schrader valve on each of the vessels.

 

[John.g]

That's great, what is the pressure on the fully charged accumulator as measured at its schrader valve?

 

[Skiddaw]

That's great, what is the pressure on the fully charged accumulator as measured at its schrader valve?

Do you mean when full? If so I cannot tell you that currently as waiting for them (or it) to fill again.

 

[John.g]

You certainly can as the pressure will start to rise immediately water starts to enter the accumulator, it will start at your precharge pressure and then rise eventually to its final pressure...exactly the same as the water side pressure.

 

[Skiddaw]

You certainly can as the pressure will start to rise immediately water starts to enter the accumulator, it will start at your precharge pressure and then rise eventually to its final pressure...exactly the same as the water side pressure.

Thank you and apologies for not knowing I could check the pressure whilst filling.

A slight different outcome currently, valves open in both vessels, after approx 15 mins, neither vessel seem to be filling at all or at their normal speed. Husband closed the valve to the vessel which has not been filling, immediately the other started filling. It is not full but current pressure is 1.75 bar. I have also checked the pressure on the other one which is also showing the same.

Is it worth draining down again and starting again, leaving both the vessels to fill for longer ( a bit annoyed husband closed the valve to the one which has not been filling!).

 

[John.g]

I wouldn't drain down again, you have pre pressurised to 1 bar which is perfectly acceptable and they are both filling so see what the final pressures are.
I am just wondering if that charging pump is variable speed controlled and some problem with this, have you any info on it?.

 

[Skiddaw]

Only one vessel is filling exactly as before.

An update, charger still running, one vessel filling, the other isn't. Pressure on both vessels 2.1 bar.

The charger has a number of settings, but speed control is not one of them. I have all the documentation for the charger so can provide answers if need be.

Another question from me, if the pressure increasing on both vessels but water only going into 1, could I be looking at something as simple as a failure of the inlet valve? Even when open is actually closed?

Thanks as always.

I wouldn't drain down again, you have pre pressurised to 1 bar which is perfectly acceptable and they are both filling so see what the final pressures are.
I am just wondering if that charging pump is variable speed controlled and some problem with this, have you any info on it?.

 

[snowhead]

Only one vessel is filling exactly as before.

An update, charger still running, one vessel filling, the other isn't. Pressure on both vessels 2.1 bar.



Another question from me, if the pressure increasing on both vessels but water only going into 1, could I be looking at something as simple as a failure of the inlet valve? Even when open is actually closed?

If the vessels start out at the same pressure empty, then during the fill cycle they both increase pressure by the same amount, that would suggest they are both filling (with something) equally.
When you say 1 vessel is not filling, how are you determining that?