Removing a Dualstream Accumulator

[wysinawyg]

We had a Dualstream (mains pressure hot water tank and cold water accumulator) installed on the new house as we were spending a packet on getting the heating re-done and didn't want to risk not having a good supply of hot water for the wife's baths.

We're now looking at re-doing the utility and after various umming and ahing the space taken up by our two massive tanks is just too much. So I'd like to try and figure out if the accumulator is really necessary given we've been in the house for a while and frankly we seem to have more of a problem with high pressure than low pressure.

AIUI (from reading and looking) the accumulator is a single bottom combined feed/exit which the installer has helpfully put a yellow handled stopcock on. Presumably by turning this handle I will cut off water to and from the accumulaotr and be able to test whether or not we actually need it.

Correct?

Dangerous?

Within the plethora of regs that now govern our lives for me to do without having my hand held?

Also do I need a (whatever the new Corgi is) plumber to remove the accumulator? Or as it isn't pressurised hot water is it okay for a regular plumber to do?

Finally, just to check, I do need a (whatever the new Corgi is) plumber to move the hot water tank itself don't I (as it is unvented)?

Cheers,

wysi

 

[Boilerman2]

Unfortunately the Lever valve you refer to is for maintenace only, the Dualstream uses the Accumulator as an expansion vessel also, so isolating this would leave your unvented cylinder without any expansion, which would cause excessive pressure to build up blowing the pressure relief valve.

So in short not a good idea, however.

If you turn off the heat source i.e. Immersion and Boiler, you can the turn off the valve to the accumulator, and whilst off measure the flow rate at your hot & Cold taps in Ltr/min, repeat test with accumulator valved on, and compare results.

Elanar.co.uk (Approved Dualstream Agent)

 

[doitall]

Just to add, whoever touches the unvented needs to Hold a G3 ticket, can be plumber or Gassafe registered.

 

[wysinawyg]

Thanks for the replies.

Not sure if it is usual or not but my tank does have a separate expansion vessel (at least thats what I assume the small tank floating above is.

Does that change things?

Also I thought the accumulator could be installed anywhere in the house, how does it act as an expansion vessel for the tank if its on the other side of the house and only on the cold side rather than hot? Is it basically just back pressure from the tank?

 

[mickyg]

if the expansion vessel above the cylinder is a white one then that'll be for the cylinder, and you can disconnect the accumulator. There's no specific regualtions governing work on accumulators, you can disconnect it and remove it yourself. The unvented cylinder needs to be moved and recommisioned by a plumber or heating engineer with G3 qualification as mentioned above.

 

[wysinawyg]

Thanks for that. Yes ISTR it is white and have also tracked down the installation instructions from the vendor which suggests it is an alternate configuration, page 4 of this:

http://www.gah.co.uk/downloads/GAH-Dualstream-technical-guide-installation-instructions.pdf

I'll take the manual home though and double check the connections.

 

[simond]

If the Ariston or OSO unvented has its own expansion vessel any plumber can remove the accumulator and no G3 cert is necessary.

If you are in my area I'll remove it for nothing, we fit hundreds of them.

But if I were you, I would turn it off first at the isolation valve and see if you can live with the basic mains supply. It might be awful.........

 

[wysinawyg]

Thanks Simon. Yes the plan is to turn it off for a few days and blind test if SWMBO notices when running her baths in the morning

After all the earache I had from her about the cost and then the "hideousness" and size of my lovely chemical factory lookalike in the utility room she didn't take kindly when I casually mentioned the idea that it might have been a huge mistake to have it and maybe we could live without it

 

[Boilerman2]

I think you will find that the separate small vessel near the tank is probably the Heating Expansion Vessel, as the Accumulator is Definately the Expansion vessel for the secondary side, so my previous advice as a DUALSTREAM AGENT APPLIES!!!!!!! :shock
P.S. The Accunulator can be the expansion vessel irrespective of where in the house it is located because No Non Return Valve is fitted betwwen the Cylinder and the Vessel, therefore water can expand and contract to the accumulator

 

[wysinawyg]

Boilerman2

I do appreciate the advice (although this maybe sounds ungrateful), but is it OSO Dualstream you do rather than GAH?

The installation manual for mine (GAH) very explicitly on page 4:

"This installation method does not allow for the accumulator to take up expansion from the unvented cylinder"

and involves putting the accumulator on the other side of the non-return valve bit of the combination valve with the expansion vessel on the other side. It definitely looks more like how mine was installed from memory, but I will have a good check and make sure I can identify the bits.

If its a heating expansion vessel where would it be located?

 

[wysinawyg]

Oh and if its a heating expansion vessel shouldn't it be bright red? or is that just custom?

This is definitely white.

 

[Boilerman2]

You tell me! as a Service Engineer I've seen allsorts so there we are, i'm getting bored now so for that reason I'm Out!

 

[doitall]

Red Vessel = Heating.

White Vessel = hot domestic water.

Blue = Boosted cold domestic water.

You will also notice the red vessel is two part and designed to separate at 6bar, I think, but t may be 7bar.

 

[AlanE]

Original poster asked if it was possible to remove accumulator.

If it was connected to cylinder using one method described in the manual then yes if the other method then no!

Nobody on a forum can actually know how this system has been installed and if it is safe to disconnect. I have a client where they have 2 unvented cylinders and 3 accumulators. Cold feeds 2 cylinder combination valves, feeds to cylinder are then joined and this common is connected to accumulators. Totally wrong according to manuals!

Best advise to OP was given by Boilerman2 get an expert in to check and advise.

On a forum enough people (with what qualifications?) reply OP gets answer eventually he is looking for none of which are based on HIS actual system. Will the installation be safe afterwards who knows!!

The installation manual for mine (GAH) very explicitly on page 4:

"This installation method does not allow for the accumulator to take up expansion from the unvented cylinder"

While quoting from the manual it also says:
BEFORE CLOSING ANY VALVE -
1. SWITCH OFF ELECTRIC IMMERSION HEATER
2. TURN OFF HEATING SYSTEM

So how do you run the house for a few days - with cold water only?

 

[simond]

Lets not get over excited about this.

In Europe the expansion vessels are often not fitted to unvented.

The OP describes a standard DualStream with a local EV; but we make up accumulator fed systems all the time using a number of makes of accumulator and it isn't always as shown in the GAH book. They no longer own the sole UK rights for accumulators.

The worst that can happen if the accumulator is the expansion vessel is exactly what happens to Megaflos after a few years the length and breadth of the country. That doesn't make them boil or become unsafe.