Sorry, maybe I have understand wrongly... they are unvented because they have expansion tanks?
When I mentioned look inside I mean unscrew the lid and look inside? Or is that not possible with these types of cylinders... haven't tried it!
Replacing two hot water cylinders with one
- Thread starter HRP123
- Start date
When I mentioned look inside I mean unscrew the lid and look inside? Or is that not possible with these types of cylinders... haven't tried it!
Sponsored Links
I'd be surprised if it's anything inside the vessel, but maybe unvented experts may disagree. IMO more likely to be in the pipework. What possible culprits are there? I've known gate valves stuck partly open.
Yeah it was a new gate valve that we installed maybe 3 years ago, so I don't think thats it but you never know
My gate valve was stuck about 1/2 open, so didn't affect the flow much. I replaced it with a 1/4 turn ball valve in case I ever needed to close it.
Sponsored Links
On the hot water outlet - I have put a picture a couple of posts above - thanks
The thing is the plumber installed these valves because of the flow issues - however they haven't made any difference since installation - if anything they have just highlighted that one cylinder is hardly draining as we suspected.
OK lets try and concentrate on the slow cylinder, so shut down the fast cylinder, ie cold supply shut.
I would then ensure that the regulating gate valve on the slow cylinder HW outlet is fully open, ie, shut it, then open it fully, there should be 3 to 5 full turns of the hanwheel between fully shut and fully open, is there??.
Does the PRV set up and E.vessel look something like the attached, can you see what setting the PRV is set to, it may be faulty??, if you have a car tyre pressure gauge then checking the E.vessel airend may give a idea of the cylinder pressure, it should vary a little if you can achieve a flow from the cylinder.
I would then ensure that the regulating gate valve on the slow cylinder HW outlet is fully open, ie, shut it, then open it fully, there should be 3 to 5 full turns of the hanwheel between fully shut and fully open, is there??.
Does the PRV set up and E.vessel look something like the attached, can you see what setting the PRV is set to, it may be faulty??, if you have a car tyre pressure gauge then checking the E.vessel airend may give a idea of the cylinder pressure, it should vary a little if you can achieve a flow from the cylinder.
It would have to be one of the other valves, or maybe some other obstruction. There are numerous pressure gauges on the system, as per your other post. Do the readings throw any light on what's happening?
I would expect a common PRV for the 2 vessels, if so it rules out a faulty PRV.
Ok so as a novice help me out here please... so we have a pressure release valve and a pressure reducing valve.
The pressure reducing valve in the diagram above is on the cold mains and is coming into the tank ... here I've noticed the sticker on one of the cold water PRVs says 3 bar and other says 3.5 bar (not sure how I would check the cold water pressure).
Then if I understand we have a pressure relief valve for the hot water in the tank. Each tank has one to release hot water from the tank itself (I have tested them by turning them to release water - both work).
By the way I have put these temperature sensors from Amazon (but I'm not sure they are very reactive) - are you perhaps confusing these with pressure gauges?
I will have a look at the expansion vessel when I get home and if I can measure the pressure using one of those tyre gauges will get one from Amazon, cheers.
The gate valves are fully open yes, they have settings from 1 to 4 with intervals of 1 to 4 e.g. 1.1, 1.2, 1.3, 1.4, 2.1, 2.2 ...
Yes just to be clear, you will/must have a pressure relief valve on both tanks, this will be set somewhere around 7 bar,
Are you saying, below, that one cylinder has a pressure reducing valve marked 3 bar and the other has another one marked 3.5bar?.
"The pressure reducing valve in the diagram above is on the cold mains and is coming into the tank ... here I've noticed the sticker on one of the cold water PRVs says 3 bar and other says 3.5 bar (not sure how I would check the cold water pressure)."
Are you saying, below, that one cylinder has a pressure reducing valve marked 3 bar and the other has another one marked 3.5bar?.
"The pressure reducing valve in the diagram above is on the cold mains and is coming into the tank ... here I've noticed the sticker on one of the cold water PRVs says 3 bar and other says 3.5 bar (not sure how I would check the cold water pressure)."
So I looked again and yes there is a cold water pressure reducing valve on the slow tank of 3 bar and on the fast tank of 3.5 bar. There is also a pressure relief valve which discharges hot water on each tank.
The interesting I just noticed is that from the cold water inlet tap upwards on the slow tank, the pipe feels warmish, all the way into the bottom of the tank. On the fast tank, the cold water inlet pipe feels cold to touch all the way into the tank itself. This means the water is not draining from the flow tank and is heating the cold water all the way back into inlet? The same inlet pipe serves both tanks, it goes first to the fast tank and then continues on to the slow tank.
Attachments
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
