Poor hot water flow from new indirect hot water cylinder

[Mini2002]

Hi Guys,
A plumbing contractor (appointed by my insurance) has just replaced the leaking indirect water tank with a new one (the brand is RM Cylinders from toolstation (please see the detail specs in this link https://www.toolstation.com/indirect-hot-water-cylinder/p62376)

On top of that the plumber has replaced the Zone valve and actuator BGMVSP-2 (which was faulty) with an unknown brand.

The issue is that the pressure performance of hot water on every single water tap become very poor and the hot water in one of the shower only running for one minute then stop. In fact, on another shower we can't get hot water flow at all.

Before the actuator Zone valve BGMVSP-2 got replaced, the hot water circulation run perfectly fine in all taps and 3 showers, including multi usage (i.e. 2 showers running and 2 water taps turning on with satisfactory performance). On that time the hot water in the the old cylinder tank was operated by turning on the central heating diverted valve instead of the hot water zone valve to initiate the boiler flowing hot water to the cylinder tank (my piping piping layout is "S-plan").

Please kindly advise what could possible the root causes and how to diagnose each of the root cause?
- Is the new RM cylinder faulty ( faulty the coils for example)? what is the indicator for this issue?
- the speed of cold water coming to the cylinder tank not fast enough? what is the indicator for this issue?
- the speed of hot water coming to the cylinder tank not fast enough? what is the indicator for this issue?
- Do I need to replace the actuator zone valve BGMVSP-2 with a compatible product, such as Drayton ZA5? I don't know the specs of the "unbranded" zone valve that is currently being put by the plumber.
- or something else?


I would appreciate for your view from experience and expertise.


Many thanks
Cam

 

[Johntheo5]

If the original valve was a BGMVSP-2, then you have a Y plan, this is a (3 port) mid position valve with three pipes, have a look at the replacement and post a photo.
Re low flow/pressure, this HW cylinder will be fed from a big storage tank in your attic, you could go to the attic and check that the outlet valves on the bottom of the cistern are fully open, there may be two, if gate type valves with a handwheel on top, there should be ~ 3 full turns between fully open and fully closed, ensure fully open (anti clockwise) also ensure cistern full, press down on ballcock to check that the mains make up is open or open a hot tap and see if the cistern starts refilling and keeps up with the demand. You may have a cold water tap in the bathroom fed from this cistern, is the flow norma?

 

[Mini2002]

Hi Johntheo,
Thank you so much for the kind sharing your expertise with me here. Many people will get benefit, blessed you.

I have never thought that BGMVSP-2 is used for Y-plan. I will post some photos of the replacement when I get home. As far as I remember, it looks similar to the below link but the motor cover is green instead of silver

BES.co.uk | Next Day Delivery On 15,000 + Plumbing Supplies

Order motorised valves and other heating valves online at BES.co.uk. Low Prices, Free Next Day Delivery Available, 15k Plus Products in stock. P/N: 17389

www.bes.co.uk

I have asked my insurance to give me the shop's name / part ID or the manufacturer's name and part number of the replacement so I can study the specs and compare it with BGMVSP-2. For example, one of Banico's valve specs can be found online (as in the attached file). At the moment, the specs of the zone valve replacement is still mystery. I have complained to the insurance company and asked them to replace with like for like product where someone in this forum has suggested Drayton ZA5 (which is proven to be perfectly compatible). The insurance company asked me to pay extra for my request but it will be refunded if my request is correct and can resolve the issue. This was the only claim originally that I made. Unfortunately, their engineer broke my hot water cylinder (which is not covered by the insurance) and I had to spend £600 (to buy a new cylinder, the fittings and cost of labor privately). I paid extra charges despite the old cylinder got leaked due to the engineer's mistake/careless.

I will take your advise to check the storage tanks in the attic, outlet valves as you described above and to do some simulation to open hot tap and checking how the cistern get refill to keeps up with the demand, etc. I will share the outcome here soon.

The cold water flowing perfectly in every room and showers, even when we open 4 taps and 2 showers at the same time. The shower flow are boosted using a shower pump, which will turn on automatically when the shower is adjusted to cold water temperature. However, in one room the shower pump will stop when the shower temperature is adjusted to 36C - 38C due to no hot water availability (I guess?). On the other room the pump run on hot water for one minutes then start cold and sometime will flow a little bit hot water for 2 second then the water gets cold again (intermittent).

Many thanks again for your thoughts and please share other possible remedies if you have. I will give you an update soon.

Best wishes
Kam

 

[Madrab]

If all just been replaced then get them back to sort it!! Complain to the insurance company if you have to. If the HW service is extremely poor compared to what it was before then they have screwed up somewhere and it's up the installer to sort it, don't accept 3rd rate workmanship. Absolutely no excuse for it!!

Sounds like it may be a supply/trapped air issue from the Cold Water cistern to the cylinder but that's just a first guess, they need to be the ones to come back and sort it.

 

[Johntheo5]

Apoligies, the above actuator is a two port.

 

[ianmcd]

The motorised valve that was replaced is a 2 port zone valve, but has absolutely nothing to do with the flow rate of hot water, it simply heats the indirect coil within the system, as @Madrab says just get them back or call the insurance company and they will get them back, they have either drawn crap in from the cold water cistern in the loft or the gate valve to isolate the HW Cylinder has went faulty when being used, or not opened fully when filling

 

[CBW]

Could be as above, gate valve that isolates the cylinder from the cold water storage cistern, likely snapped. Was it not tested before the insurance person left?

 

[tincup]

My guess air lock.

 

[HERTS P&D]

Try this:

Removing an airlock through a mixer tap youtube - Google Search

Andy

 

[tincup]

Prepare to get wet

 

[ianmcd]

On top of that the plumber has replaced the Zone valve and actuator BGMVSP-2 (which was faulty) with an unknown brand.

maybe unknown to you but not to the pros, post a pic of it and we will tell you what it is

 

[Mini2002]

Hi Guys,
I would like to ensure that the plumber has installed the correct actuator for zone valve before I start working on the system.

Please find attached the picture the old and new zone valve and the actuator. Also, in the report it is clearly stated that the engineer identified "faulty 3 zone valve" despite BGMVSP-2 is for 2 port. what if the new actuator (blue color) is actually for 3 zone valve, does if affect the flow performance of water from the boiler to the cylinder tank?

I appreciate your kind view and sharing expertise.

Thanks
Kam

 

[Johntheo5]

The above, only opens/closes to control the temperature of the HW, not its flow rate, which has allready been pointed out.

 

[Mini2002]

Thanks John.
In the link below, the maximum temperature for Honeywell Home V4073A Motorised 3 Port Mid Position Valve 22mm V4073A1039 is 50C

Honeywell Home V4073A Motorised 3 Port Mid Position Valve 22mm V4073A1039

The Honeywell Home V4073A motorised 3 port mid position valve, 22 mm, is used in conjunction with a room thermostat and a cylinder thermostat to offer full temperature control of a conventional, fully pumped central heating installation. The valve has been designed to control the flow of water...

www.cityplumbing.co.uk

Where BGMVSP-2 can operate up to 95C

Drayton 22mm 2 Port Zone Valve BGMVSP-2 | Wickes.co.uk

Drayton 22mm 2 Port Zone Valve BGMVSP-2

www.wickes.co.uk

Does the maximum operating temperature affect the open/close the valve or the rate of water flow from the boiler to cylinder?

Thanks
Kam

 

[Johntheo5]

It doesn't matter whether it does or not as that water flow is through the heating coil and returns to the boiler, it has nothing to do with the domestic hot water flow from the cylinder.