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Hi there, I hope you can help please!

I wanted to check whether the following seems reasonable before I spend more £ calling a G3 engineer out. Any help would be really appreciated.

I have an Albion unvented system (hopefully the pictures help). Over the last week or so, almost 12 months to the date since its last service (typical!) I noticed my tundish dripping, and a weird hissing noise. Turns out the expansion vessel had a teeny hole in the bottom and was oozing rusty stuff.

I called an engineer today who has replaced the vessel (the new blue one in the picture), and so far it seems ok. Hot water is back, tundish is still damp from when it was dripping but appears to have actually stopped the drip.

My question is what the pressure valve pictured should actually be showing? The engineer told me the max it should ideally go to is 3, but when I got home this evening it was just over 4.

Any ideas!?

I'm away this weekend so it's worrying me!!

The rust marks aren’t from this - they’re from years back before I bought the property FYI.

Thanks in advance,
Dan

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Thanks Riley.

It’s the only gauge there, what do you think, should I not be worrying too much about what that says (ie if it’s 4) as long as the tundish is dry?
 
You need a G3 Engineer to look at the complete set up of your tank and to verify it is ok / correct it. It is difficult to do a proper / complete diagnosis from photographs.

Having said that, I have a number of points that he / she should address:

The pressure at the gauge is determined by the preset combination valve ( the large valve with the grey top and the small red valve immediately beneath it) It is normally not more than 3.5 bar. Look on the valve ( on the grey top) and it will be marked as to what it is set at. As Riley as said the pressure gauge is in a silly location and will be affected by temperature - but in your case, I don’t think that is the only issue

Your system looks to have plumbed rather oddly ( and possibly modified since original installation). There should not be any pipes other than the feed connected between the combination valve and the cylinder inlet. You have one or two pipes branching off this feed. If they are taking cold feed water, it will reduce the performance of your system, but they may be or have the potential to deliver water to the cylinder under mains pressure circumventing the combination valve. If it is the latter it could result in a pressure in the cylinder above the rating of the combination valve.

Balanced cold should should be taken from the connection to the rear of the combination valve not the tank feed.

It looks as if the combination valve has been replaced at some point and moved to a position some 12 inches above its original position. At that time perhaps the connections were made incorrectly.

On a final point. On the side of the tank is a red valve (it is a P and T safety valve) with a 15mm pipe running from it. Does that pipe go to the tundish? From the photo it looks as if it is connected to the cold feed - but that may just be a trick if the light. It is important that the 15mm blow off pipe from that valve MUST go to the tundish.

Sorry to be a little alarmist - I hope I am wrong about the safety valve
 
Your system looks to have plumbed rather oddly ( and possibly modified since original installation). There should not be any pipes other than the feed connected between the combination valve and the cylinder inlet. You have one or two pipes branching off this feed. If they are taking cold feed water, it will reduce the performance of your system, but they may be or have the potential to deliver water to the cylinder under mains pressure circumventing the combination valve. If it is the latter it could result in a pressure in the cylinder above the rating of the combination valve.

Balanced cold should should be taken from the connection to the rear of the combination valve not the tank feed.

Morning brambles, that’s not quite true. It’s perfectly acceptable to have a balanced cold taken off the supply pipe after the PRV. There’s many a cold set that doesn’t even have a tapping for a balanced cold.
 
Looking at the control block, that has never been serviced. Depending upon its age, it is likely that flow will be reduced due to a partially blocked filter.

My two penneth re the set up.
1 - I'd like to know the pressure in the vessel. As most come set to 3 we can prob assume it's that.
2 - I'd like to know PRV operating pressure.
3 - the expansion should then be set a little higher otherwise it cannot operate as an expansion vessel!
Those measurements need to be done.
With regard to the CW take off, the reason its done at the control block is that the PRV only passes a certain volume. This means if you take of the CW after the PRV, it can possibly reduce HW system performance. By taking it off at the control block, (before the PRV in flow terms) they assume the incoming main flow is capable of supplying over and above the HW requirements.

Hope that makes sense o_O

BTW - I'd def get rid of those dead legs. That's sheer laziness.
 
That pressure gauge is your mains pressure.
Open a tap and it should be on 3 bar, when shutting tap it may go up to 4 bar but that is normal.
If when tap is open the pressure is above 3 bar then call an engineer to have a look at combination valve.
Not many engineers put a pressure gauge on mains but really handy to have.
 
That pressure gauge is your mains pressure.
Open a tap and it should be on 3 bar, when shutting tap it may go up to 4 bar but that is normal.
If when tap is open the pressure is above 3 bar then call an engineer to have a look at combination valve.
Not many engineers put a pressure gauge on mains but really handy to have.

Sorry to disagree Jase but it's not. It's placed after the control block. The NRV in the control block would mean the gauge remains stable to any cold water use. It would only time it would drop is on HW use.
 
Sorry to disagree Jase but it's not. It's placed after the control block. The NRV in the control block would mean the gauge remains stable to any cold water use. It would only time it would drop is on HW use.

Would rise when the water is being heated tho
 
Hi there, I hope you can help please!

I wanted to check whether the following seems reasonable before I spend more £ calling a G3 engineer out. Any help would be really appreciated.

I have an Albion unvented system (hopefully the pictures help). Over the last week or so, almost 12 months to the date since its last service (typical!) I noticed my tundish dripping, and a weird hissing noise. Turns out the expansion vessel had a teeny hole in the bottom and was oozing rusty stuff.

I called an engineer today who has replaced the vessel (the new blue one in the picture), and so far it seems ok. Hot water is back, tundish is still damp from when it was dripping but appears to have actually stopped the drip.

My question is what the pressure valve pictured should actually be showing? The engineer told me the max it should ideally go to is 3, but when I got home this evening it was just over 4.

Any ideas!?

I'm away this weekend so it's worrying me!!

The rust marks aren’t from this - they’re from years back before I bought the property FYI.

Thanks in advance,
Dan

View attachment 38984

View attachment 38985

View attachment 38986

This thread may be worth a read....
Unvented cylinder relief valve letting by
 
Hi Dan
The guy you had change the vessel & carry out the service last year were they G3 ?
If so it is rather disappointing that they didn't pick up on the faults on your system. Most have been covered above but let me just list & clarify them for you.
  1. No cold water (balanced) connections should have been taken of the cold feed pipe between the cylinder & the composite valve set, the reason for this is it breaks the Water Regs as it would allow hot water from the cylinder to back flow in to the cold pipes. The composite valve contains a non-return valve located before the pressure relief safety valve but after the balanced cold water port provided. As Bogrodder committed some composite valves don't come with a balanced cold port but in this case a single check valve would need to be provided & most importantly the pressure relief safety valve would need to be moved to the cylinder side otherwise it is isolated from the source of expansion.
  2. Can't see a tun dish & one should have been installed within 600mm of the T&P safety valve sticking out of the cylinder. It allows you to see if either safety valve is discharging & provides an air gap break to stop contaminated water getting back into your system.
  3. The gauge is very useful to an engineer it can tell you what is happing in the system & I wish more were fitted. It is showing 3bar in the photo so we can assume the PRV in the composite valve is a 3bar type & is working correctly. The pressure rises a small amount as the water in the cylinder is heated by the immersions the amount of rise should be limited by the expansion vessel, if set up correctly. I would expect to see a 0.5 - 1bar rise all things being equal, open a hot tap (or the incorrectly installed balanced colds) & the pressure should fall back to around the 3 bar mark. If it falls down lower with a tap open it could indicated a poor flow through the mains, possible a blocked filter etc. If it rises higher than 4bar under heating then it would indicate the vessel needs servicing etc.
So much info from a small cheap gauge, if you know what you are looking at!!

PS. another incorrectly installed filling loop :eek:
 
Thanks all for your help with this!

I won’t lie and say much of this makes sense, but just to add to this:

Yes, as soon as a HW tap is run it’ll drop down to 3 or just under.

The image attached showing 3.5ish is when I got up this morning (so before any water was run - so an overnight result pressure).

I’ve taken a pic of the bits above the gauge - it shows the valve as 6 bar and the bit above it appears to be a filter.

The tundish has stopped dripping. It is located to the right of the cylinder from a pipe around the back - from what you’ve said this pipe appears to be too long.

My question would be how urgent do you think this work needs doing? It doesn’t sound like it’s failing by your above comments and I’m away this weekend, so should I be panicking to get a G3 engineer out, or is it something to fix soon? If anyone is Hertfordshire based let me know, you guys seem a million times better than the G3 engineers that I’ve had come out!

Thanks again!

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The T&P safety valve in your cylinder is 90C/7Bar, there should be a label on your cylinder stating the design pressure, if it is < 7 bar then that alone would be a major safety issue.
 
Dan

There are a number of issues with the installation of your Un Vented system. I think that the forum have gone as far as they can to point you in the right direction - further posts will probably start to confuse matters for you.

I would suggest that you have your break, turn off the water heating and cold water inlet for peace of mind if you wish. Upon your return get a good G3 to look over and correct your system - it is not a difficult job.

If you message me ([email protected]) I can give a recommendation if you wish
 
Dan
There are a number of issues with the installation of your Un Vented system. I think that the forum have gone as far as they can to point you in the right direction - further posts will probably start to confuse matters for you.
I would suggest that you have your break, turn off the water heating and cold water inlet for peace of mind if you wish. Upon your return get a good G3 to look over and correct your system - it is not a difficult job.
If you message me ([email protected]) I can give a recommendation if you wish
Spot on advice Brambles, go enjoy your holiday Dan although incorrect no major issues.
 
Thanks all. Really appreciated. I will email you now Brambles.

Re the cylinder I’ve attached the spec. The red valve on that is 7 bar.

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DA4532E1-543B-4481-AF9E-599E5CAC7490.jpeg
 
Dan

There are a number of issues with the installation of your Un Vented system. I think that the forum have gone as far as they can to point you in the right direction - further posts will probably start to confuse matters for you.

I would suggest that you have your break, turn off the water heating and cold water inlet for peace of mind if you wish. Upon your return get a good G3 to look over and correct your system - it is not a difficult job.

If you message me ([email protected]) I can give a recommendation if you wish

Brambles. Be careful about 'recommending'. From painful personal experience, Vicarious Liability rears its head. Give more than one and make it clear the choice is theirs. Giving one name is a recommendation in law. ;)
 

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