This low system pressure was the OP symptom however not everyone knows that a faulty diverter valve can allow pressure to drop slowly and not cause any evidence of a leak.
****ing boiler system...
- Thread starter Cozzer
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Stevekane
Established Member
When my sons shop was suffering from very low water presure around late afternoons we contacted the water company who were happy to send out an inspector who checked the presure on the premises, there was no charge for this, might be worth doing.
Steve
Steve
John Brown
Freeloading Social media influenza
Diverter valves are the work of the devil.
porker
Established Member
Same guy as @Sachakins showed has a video showing this valve.
Diverter valve
I agree with the previous posts. Looks like you have two issues - water pressure and a separate leak on your CH. I would have thought a plumber would know to check the diverter valve (if you are topping up daily I would expect there to be signs inside the boiler casing) and the expansion vessel. If it's in the concrete floor you have my sympathy as I've had to deal with that in the past. Probably a job for the summer when you can shut down the heating and pressure test the pipework under the floor. I've done this in the past using a pressure meter as shown earlier but it means cutting pipe. In my case, the copper was buried in the concrete with no protection at all and concrete severely corroded the copper. I fixed it by bypassing and running pipework above the floor.
Another possibility is to find someone with a thermal imaging camera as they may be able to spot the issue with minimal disruption. I know a lot of plumbers use them to diagnose these sort of issues.
Diverter valve
I agree with the previous posts. Looks like you have two issues - water pressure and a separate leak on your CH. I would have thought a plumber would know to check the diverter valve (if you are topping up daily I would expect there to be signs inside the boiler casing) and the expansion vessel. If it's in the concrete floor you have my sympathy as I've had to deal with that in the past. Probably a job for the summer when you can shut down the heating and pressure test the pipework under the floor. I've done this in the past using a pressure meter as shown earlier but it means cutting pipe. In my case, the copper was buried in the concrete with no protection at all and concrete severely corroded the copper. I fixed it by bypassing and running pipework above the floor.
Another possibility is to find someone with a thermal imaging camera as they may be able to spot the issue with minimal disruption. I know a lot of plumbers use them to diagnose these sort of issues.
I’d definitely confirm the water supply pressure 1st . As I recall there can be several reasons for f22 anything from low pressure to poor circulation. So worn pump or sludge in the system . Sludge can produce hydrogen which can be expelled by the boilers auto air vent which will then reduce the system pressure. It’s too easy to say it a leak or it’s the diverter or the expansion vessel is leaking. A through investigation is required by a heating engineer not a plumber ( no disrespect) . But as the water mains supply is suspect that’s where I would start . Then a logical investigation from then on to rule out the possible suspects. Also worth noting that heat exchangers can leak and drain via the condense trap and out into the waste and you’ll never know ..best way to confirm if the system is leaking is to isolate the flow and return and pressure test the system to 2bar for 10 mins with no drop at the gauage . A new system could then be tested at 10bar ( recommend by s g speedfit but I’m not sure I’d risk this on an existing system unless you can verify the integrity of the pipework and joints . Once you confirm the system is sound (at 2 bar ) then as long as it’s clean - no black sludge or cold spots on the rads your left with the boiler . With the heating off- rads cold run the hot water tap - the hot water outlet from the boiler is the only pipe that should be hot - if the heating flow is warm or worse hot ghen the diverter is passing to heating and will need to repaired or replaced. I,m not 100% on this but if you set pressure on the boiler to 1.5 bar and isolate the flow and return any pressure drop would indicate a leak from the heat exchanger . ( a rise in pressure would indicate the filling loop is passing ( meaning the pressure would always be as high as the mains pressure. Hope this helps ..
Cozzer
Established Member
The bain of the combi boiler and a good reason to use a system boiler with Honeywell zone valves and no divertor valve.
Very frustrating! Various observations, ideas and possible next steps as I do think you've got quite a few options to move this forwards:
- Having had various gas engineers over the years, I definitely think it’s time for a second opinion. They don't all think the same and diversity of opinion is a good thing. Without digging at your current gas engineer, just a fresh pair of eyes can be helpful from a problem-solving perspective. Ideally a fully registered Vaillant engineer though.
- Also, the other thing that confused me was you’ll have been covered under a Vaillant guarantee with their own engineers as you had the boiler installed. And if the boiler is still only 5-6 years old, you're still covered for at least a year. If your engineer isn't a full Vaillant, though, you may only have a 2-year guarantee. If they can't prove there is a leak under the floor, they should have at least swapped the usual suspects in terms of parts under the guarantee to rule them out, especially as it only started when you had the new boiler. As has been suggested here, the expansion vessel/valve and the diverter value could both be culprits.
- If you're putting essentially a cup or more into the system a day to top it up, that's quite a lot of water to be pumping into your floor if it's a leak. Even with a conservative estimate of say 200ml a day, you've probably pumped over 10-50 litres into the system, if not much more over the last few months! If there is a specific leak in the concrete a damp meter should be able to show at least some discrepancy in terms of moisture under the floor given that level of water being leaked in (if it is that).
- Your engineer's issue of not being able to find anything is kind of fine, but at the same time he's there at a particular time in the day, probably when the heating has been on and everything has expanded. We had an issue with our expansion vessel and valve, but the number of gas engineers that didn't check with surprisingly high (had British Gas and SSE boiler cover). Given it's covered under guarantee, and it *could* be that but it's hard for them to tell for certain, I'd expect them to change it out just in case.
- If you isolate your boiler over-night from the central heating using the two levers under the boiler (at least on a baxi) does the boiler lose pressure overnight on it's own? If it doesn't, then I guess it could be a central heating leak. If it does lose pressure on it's own, then I'd guess it's the boiler. (This is a working hypothesis - someone can correct me if I'm wrong but when I drained the central heating system the gas engineer showed me how to isolate the boiler by closing the two levers. That way the pressure was held at the correct level for the boiler but I could still drain the system. Can't remember if the hot water still works but I seem to remember it did. You'd need to turn the thermostat off so it didn't try to run the central heating when it was isolated from the rest of the system). If it's held pressure overnight being isolated, I'd expect opening the pressure to drop right down when the boiler valves were opened again if it's a leak. If you try this, take photos and even a mini video at each stage to prove you aren't making it up. If you wanted to rule out external water supply issues, you could close the stop cock overnight too. Just fill up some buckets of water to manually flush the toilet overnight and fill the bath to be able to wash your hands.
- The low pressure on your washing machine and taps sounds like a different issue that needs looking into unless you're talking about hot water supply line/tap rather than your cold supply. Testing out the water pressure as suggested is a good plan (on the cold supply only).
- I don't feel that your gas engineer has been particularly systematic about ruling things out, and just goes for the 'obvious' answer each time. Problem solving is a skill, as is thinking creatively about how to rule things in or out. He hasn't done this. Being a good problem solver is different to being a reliable gas engineer.
- I would suggest contacting Vaillant and making quite a fuss. This shouldn't be happening for a 'from new' boiler, and they need to make it right. Didn't happen with your old boiler. Started with your new boiler. Slowly got worse. They also have a list of approved 'advanced' engineers that would be covered/send out under your guarantee.
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Cozzer
Established Member
Only 1 year guarantee with Vaillant, Matt....
Agent_zed
Established Member
Whilst you are waiting to sort that out I'd consider fitting a water hammer arrestor like this https://www.screwfix.com/p/sioux-ch...1pgBdUoMY6BZNzyo2fhoCdugQAvD_BwE&gclsrc=aw.ds. All the banging and movement of pipework has the potential to break solder joints and cause even more problems down the line
Cozzer
Established Member
Thanks, Agent_zed...that's interesting.
To a total non-plumber, it's great that you lot on here know about these things!
Just as an update, we haven't suffered an F22 since laddo used the anti-leak stuff. Whether that actually proves it was (just?) a leak, I don't know.
The downstairs stop tap is getting gently tweaked more open every other day, with the interim thought that the day the banging comes back, it'll get gently tweaked back...but at least we can flush the toilet and use the sink hot tap at roughly the same time. Luxury indeed!
The upstairs shower is kaput though. Water flows, but doesn't get hot. Something to do with old-size piping and thermostatic valves. Unfortunately the thing's mounted on a totally-tiled wall, so for the minute it's out of bounds!
Agent_zed
Established Member
By the sounds of it you have air in your system which was causing the banging but I have seen it where a worn valve caused the banging/vibration. My old tap used to do it when the rubber washer was worn out and my parent in laws header tank valve on the ballcock did the same. Both instantly fixed once the valves/washers were replaced.
Anything that also shuts down the flow quickly, like the washing machine inlet valves, can cause water hammer. There is a fair bit of energy involved. There is quite an interesting invention that uses water hammer to lift/pump water using only the energy of the flowing water being stalled. https://en.wikipedia.org/wiki/Hydraulic_ram nothing to do with your problem but interesting if you like that sort of thing.
If the problem is new then something has changed and rather than fit a hammer arrestor it would be better to look for the cause of the problem which can be trapped air in the pipework or lose pipework first. If there is any leak in the system not only can water escape but air can be drawn in but it sounds like the leak fix liquid has given you a temporary solution to this.
Have you determined your water pressure to your property ? Have you checked the main stop cock is open completely as they often seize.
Agent_zed
Established Member
agreed. My suggestion was more an immediate fix/protection whilst the other problem is sorted. I was probably thinking of it from my position where I would fit this myself without the need of a plumber. I think some of them like this one can just be added to the end of the washing machine connection without much knowledge. Just turn the valve off, screw this on, reconnect pipe to washing machine. (Also assuming there is enough space to fit it)
They are also useful in the long term for water hammer in general but hopefully not to the extent the OP is currently getting.
Cozzer
Established Member
The main one?
You mean on the pavement at the house front? If so, no....
From what you write, that should be fully open?
I mean the pressure your side of the main stop cock, it should be good at the water companies isolation valve / meter outside your property but from there it goes down a smaller pipe to your stop cock. You can get a pressure tester quiet easily that you could connect to your boiler fill loop that will determine if pressure is the problem, https://plumbingsuppliesdirect.co.uk/rothenberger-mains-water-pressure-gauge-0-10bar-0-150psi/
Cozzer
Established Member
Ah...you mean the one under the kitchen sink, then!
No, that's virtually closed. As I mentioned above, at "5 past the hour" it's closed. Nothing gets through. On the hour, we get water, but it's a dribble. Currently it's (maybe) 3 minutes to. At 5 minutes to, all hell breaks loose!
okeydokey
Established Member
Vaillant UK have a service department https://www.vaillant.co.uk/service/annual-servicing/
It may be worth getting them to service the boiler and it will put beyond doubt if there is a problem with the actual boiler.
As a side issue have you bled the radiators (starting at the highest one in the house that will establish if there is air in the pipework generally.
It may be worth getting them to service the boiler and it will put beyond doubt if there is a problem with the actual boiler.
As a side issue have you bled the radiators (starting at the highest one in the house that will establish if there is air in the pipework generally.
Stevekane
Established Member
First appologies for yet another probably completly daft suggestion, but there is I suppose, no chance that your stopcock, under the sink could have been fitted backwards?
Steve
Steve
