Help required to identify a valve on Hot Water Draw-off

[Harvest Fields]

They will only replace what is faulty.

 

[Welder]

Three pressure reducing valves!? I cannot for the life of me work out why so many.

First, so long as the control block & tprv is fine 8 cannot tbink of a single positive reason for more unless local pressure is so high it warrants one one the incoming main to ensure absolute max performance...

The prv on the output actually looks new which sets me thinking that there may have been previous issues yet to be clarified....

 

[rpm]

They will only replace what is faulty.

It`s only faulty because muppet took it apart and now it leaks!

 

[Steve-Scotland]

The unknown one on the output has always been there as far as we can remember (I'm not aware of any previous issues that may have warranted the fitting of it, and we bought the house new).

The only way I can work out why its there is possibly to regulate the pressure between the infill to the tank and the outflow to the taps/showers -

Now again, I have absolutely no background in heating/hot water so could be completely off here - but by my reckoning, if the outflow pressure is greater than the infill, then could this be the reason why the hot water pressure at the taps is low (i.e. turn on tap, works well for 20 seconds but then tails off, and then after closing the tap for a couple of minutes, this allows more water to flow in to the tank, building the pressure back up so that again when the hot tap is turned on, the pressure is okay for 20 seconds). So by replacing the large known PRV (if this is faulty and reducing the pressure in), this would hopefully resolve our low water pressure issue).

Finally, if the unknown valve (PRV on the outflow) is replaced by a piece of pipe, would the pressure be equal (i.e. 3 bar in = 3 bar out), or is it possible we could still have an imbalance (i.e. more out than in) and still have the same issue with low water pressure? The reason I ask, is I don't know whether it would be better to insist for him to replace like for like instead of removing and replacing with pipe.

Thanks again

 

[CHRISX]

Three pressure reducing valves!? I cannot for the life of me work out why so many.

First, so long as the control block & tprv is fine 8 cannot tbink of a single positive reason for more unless local pressure is so high it warrants one one the incoming main to ensure absolute max performance...

The prv on the output actually looks new which sets me thinking that there may have been previous issues yet to be clarified..

Hello YorkshireDave / Steve-Scotland [the OP],

As You intimated Dave no Plumber is going to put a Pressure Reducing Valve [Honeywell DO5] on the Hot Water outlet unless there have been previous problems caused by the water pressure on the Hot Water supply pipework - especially as You have also mentioned there are 2 other Pressure Reducing Valves on the Mains pipework.

However - before just `removing it` a Plumber should investigate why it was fitted in the first place.

IF it is just removed there may be an immediate problem with the Hot Water pressure.

To Steve-Scotland [the OP]:

This is where I have to advise that a Plumber is employed because they will be able to look at the Plumbing / Pipework etc. in your Home and will have a better understanding of the RISKS associated with what I am suggesting:

I would suggest `experimenting` by very gradually increasing the pressure on the Pressure Reducing Valve - that is going to be better than just removing it and `hoping for the best` !

I would advise that when the original problem is fixed by BG some investigation is done by gradually increasing the pressure on the Honeywell Pressure Reducing valve to see if anything happens regarding too much pressure at the Taps / Shower etc.

Before doing that `Test` I advise that the Washing Machine / Dish Washer water supply valves are closed and the hoses disconnected from the valves as a precaution to eliminate any chance of the hoses bursting or damage to the Appliances - because I would not rely on standard quality Washing Machine valves to hold back possibly very high pressure while the `Testing` is going on.

`Better be Safe than Sorry`.

Something else that occurs to me while writing this is that IF the incoming Mains water pressure is so High that it requires 2 x Pressure Reducing Valves BEFORE the Unvented Cylinder / Megaflow and another after it is there a possibility that the Unvented Cylinder is still being fed with Mains water that is under too much pressure for the Cylinder specification ?

Chris

 

[quality]

call a local engineer and get rid of BG

 

[Harvest Fields]

call a local engineer and get rid of BG

they May get the same bloke backnif it was a contractor
I’m out

 

[quality]

That is not my problem but theirs but my advice not yours

 

[CHRISX]

Hello All,

Further to my previous message:

Looking more closely [at the photo] - the Pressure Reducing Valve setting Dial - does it look like it is already set at approaching either `5` or `6` ?

Chris

 

[Welder]

Hello All,

Further to my previous message:

Looking more closely [at the photo] - the Pressure Reducing Valve setting Dial - does it look like it is already set at approaching either `5` or `6` ?

Chris

Here goes - frankly its got more less chance of being true that one of Donald Trumps tweets...
How about:
Symptom is severely reduced flow. Possibly strainer on incoming main partially blocked and potentially that in the control block too. So, instead of cleaning out and descaling the filters they've simply upped the set point on the PRVs so it 'improves'. That however gives too much initial flow (especially if the pressure vessel has failed too) so the whack in the PRV on the outlet! Told you it was nuts!

Of course the problem there would be the pressure relief valve in the control block. That normally starts weeping. As we haven't seen the tundish we have no idea one way or other its state. Not being a betting man, I'd put my 10p on it being scaled.

IF that's the case then its a new block, sort vessel, sort incoming main filter & rip out the abomination on the OP.

Chris. It can't go over pressure for the cylinder as you have two protections.

OP - I'm already sure of this answer, but when was this system last serviced? I can see the optimistic emojis flooding in