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

[Steve-Scotland]

Hi there,

Hoping someone on here could assist with a query I have regarding a valve on our hot water draw-off from our Megaflo system.

Have called out British Gas Homecare engineer as hot water pressure has decreased on all taps/baths/showers to the point that it takes ages to fill bath/sinks or (mixer) shower is running tepid.

Long story short, he is going to replace a large pressure relief valve but as part of his investigation he noticed another valve on our 'hot water draw-off'.

He didn't know what it was (thought it looked like either another PRV or a Mixer valve) but couldn't understand why this would be on the hot water draw-off - He called a couple of guys who could not identify it or its purpose.

He removed it to check it and it appeared clear, but when he to put it back in place, it started leaking when the cold water infill was turned back on.

He has said that when the other PRV is being replaced (tomorrow), he will take the leaking valve out and replace with a piece of pipe.

I'm looking for help to identify what it is, and would it be safe to remove it and replace with pipe (I'm thinking it must have been put in for a reason)?

Any help that anyone can provide would be greatly appreciated.

Many thanks

Steve

PS If it helps, he said there appears to be 3 pressure relief valves on the system - 1 at the main stopcock into the property, 1 big one on the Megaflo (which is the one he is going to replace), and this possible one on the draw-off.

 

[townfanjon]

Edit.
Wrong thread.

Shakes his head lol

 

[rpm]

Edit.
Wrong thread.

Shakes his head lol

Correct person, just wrong thread

 

[Steve-Scotland]

Hi there,

Don't worry, I have absolutely no intention of trying to fix anything related to to Central Heating or Hot Water, I was really just trying to get confidence that the valve could be removed safely and replaced by pipe without me being woken one night by a boom or a cascade of water running down my hall.

I've just checked with one of my neighbours that has the same house style and set-up as me, and it appears that he does not have this valve on the hot water draw-off so am now a bit more confident that if he can live without it, then so can we (unless someone wants to say otherwise).

Once again, I really appreciate everyone's input on this - Thank you all

Cheers
Steve

PS. I'm now 99% sure it's a Boss Pressure Reducing Valve

 

[steadyon]

Its a Honeywell D05F pressure reducing valve. Odd to have it in the output from an unvented cylinder, normally the pressure reducing valve is on the inlet.

 

[Steve-Scotland]

We do have 1 on the inlet also - that's the one that he is going to replace tomorrow (as he had to order the part) - just need to have a night off from hot water - oh well, at least it gives me a reason to use my gym membership tonight (for the 1st time in about 2 years) lol

One other question, would it be better to ask him to replace the 'unknown' one with another of the same type to save any potential future issues?

 

[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

 

[Steve-Scotland]

Hi there,

TBH, I'm not sure it has been serviced (apart from the general annual service that we get from BG but that seems to be concentrated on the boiler in the garage) - should I be asking them to service the megaflo at the same time?

Re the setting on the PRV, it has been turned down as the water is now off, as it was leaking so the value currently showing on it is not what is was at pre-removal.

The Tundish appears to be fine - please see pics

Also, have not been aware of any dripping into the tundish.

Thanks
Steve

 

[CHRISX]

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

Hello again YorkshireDave,

What a good `Diagnosis` very well described - I was in total agreement with what you explained until I posted this message and saw that the OP / Steve had posted photos of the Tundish.

However as You pointed out probably the most frequent cause of loss of Hot Water volume to the outlets from a Megaflow is a blocked / scaled inlet filter - it should have been the first `Check` carried out.

I worded my comment about the inlet pressure to the Unvented Cylinder very badly - I was being rushed by `She who must be obeyed` to sit down for Dinner.

I was trying to think along the lines of - is the inlet pressure very close to the specified `Maximum Inlet Pressure` and are there occasions when without the OP knowing the PRV is discharging and when the Cylinder pressure is being `relieved` that affects the Hot Water draw off pressure & volume ?

I then realised that the PRV would not be releasing enough water / pressure to affect the Hot Water pressure / volume.



Chris

 

[Welder]

Something has been letting by into the tundish - but not for long looking at it. No evidence of long term discharge which makes it all the more puzzling tbh...

With no servicing having been carried out, that'd still be my first port of call - a proper and extensive service. At that point I'd review whole system performance and change controls to suit. Still got my 10p on removing that redundant PRV... possible another too.

Steve. You need to get an experienced G3 engineer on to this. If you check your BG contract, I'd be very very surprised if your UVC is covered. Personally, I'd look for a suitable local engineer and get it done properly and annually so you and your family are safe into the future.

 

[Harvest Fields]

Something has been letting by into the tundish - but not for long looking at it. No evidence of long term discharge which makes it all the more puzzling tbh...

With no servicing having been carried out, that'd still be my first port of call - a proper and extensive service. At that point I'd review whole system performance and change controls to suit. Still got my 10p on removing that redundant PRV... possible another too.

Steve. You need to get an experienced G3 engineer on to this. If you check your BG contract, I'd be very very surprised if your UVC is covered. Personally, I'd look for a suitable local engineer and get it done properly and annually so you and your family are safe into the future.

I think this conversation has been going on long enough in an open forum boys and girls if there is any on here.

 

[chris watkins]

We do have 1 on the inlet also - that's the one that he is going to replace tomorrow (as he had to order the part) - just need to have a night off from hot water - oh well, at least it gives me a reason to use my gym membership tonight (for the 1st time in about 2 years) lol

One other question, would it be better to ask him to replace the 'unknown' one with another of the same type to save any potential future issues?View attachment 35071

NO

 

[ShaunCorbs]

The only thing I can think of that your builder / plumber has done when he built it is teed off for the balanced colds before the pressure reducing valve

Which has been causing problems with the cold overpowering the hot eg hot tap running cold on mixed, so they've put another reducing valve before the tee off

Best thing you can do is ask for a more experienced engineer to come out and have a look as your not happy

Also any parts they replace will have to be from the manufacturer to keep your cylinder warranty eg the black mono / control block one megaflow


Will leave this thread open for now but I'm keeping my eye on it

 

[Welder]

.
Best thing you can do is ask for a more experienced engineer to come out and have a look as your not happy

Will leave this thread open for now but I'm keeping my eye on it

Agree. Good engineer reqd asap. End of.

 

[Harvest Fields]

Agree. Good engineer reqd asap. End of.

Think I said this in about post 7

 

[dan_the_plumber]

That engineer may be qualified but is not very good.
That valve is a pressure reducing valve. If it’s on the Domestic hotwater outlet then it’s been installed in the wrong place. The engineer may be right that it needs taking out and just pipe out in.
HOWEVER....He needs to have a look at the manufacturer’s instructions and replace and parts with genuine parts meant for that cylinder.
They need to be replaced in the correct order and according to G3 regulations!

 

[rpm]

Well this started Wednesday with the engineer due back on Thursday so any update OP?