I think my hot water cylinder hasn’t been plumbed in properly

[pspec]

.

I think my hot water cylinder hasn’t been plumbed in properly …


It’s a dimplex unvented mains pressure one (with a pump to make a hot water ring/loop so you have instant hot water at all taps).


First the problem (oh I should say I keep the loop thing turned off)


Most of the hot water taps temp are about 35% colder than if the loop is tuned on and it doesn't matter how long you let it run for it wont get hotter..


When running kitchen tap you need to run around six buckets of water before it get warm and it never seems to get really hot…


So this loop thing


Hot water comes out the top of the tank runs to all the taps then to a pump then it joins the cold water feed that goes into the bottom of the tank. I’m calling it a loop as I don’t know its proper name and it seems to make a loop so loop it is…


I’m thinking (with the pump turned off) when you turn a tap on its drawing hot from the top and cold from the bottom and that’s why I’m getting this 35% temp drop. The kitchen tap I think could be at the end of the loop and therefore closer to the cold so it could be drawing more cold than hot…


I’ve found an old Dimplex manual that shows there should be a one way valve before the hot water pipe joins the cold on its way back into the tank.

If I’m correct by adding a one way valve I think this should sort out the problems.


But I’m not sure if it already has a one way valve so I’ve posted photos showing the pump and the pipes going back to the hot water tank. It doesn’t look like there's a one way valve but then I’m not sure what it would look like. On both sides of the pump there are a large copper type joints that joins the pump to the pipe could the oneway valve be in one of them..

Second possible problem….


Looking at the above diagram it shows a swept Tee joint where the hot water return joins the cold pipe


As you can see in the photo above I have a Tee joint installed there. Would this course a problem..


Sooooooooooooooo

I’m I correct and I don’t have a one way valve and I do need to install one…………….???????????????

Also the diagram shows the one way valve installed after the pump. can I install it before the pump as there’s no room to do so before it without ripping the whole thing apart………???????????????????????

Can I leave the Tee joint on the in feed pipe or do I need to change it to a swept tee joint………??????????????

Thanks

 

[Stigster]

You are missing the non-return/check valve between the pump and the rad handled ball valve below the pump.

It would take some very minor alteration to the pipework to make space to fit one between pump and red handled valve.

Unfortunately you can't cut a check valve in to the 22mm cold feed where it enters the bottom of the cylinder (not that you suggested it but someone incompetent might suggest it!) because that would stop you being able to drain down the tank for future maintenance. That would also create a dangerous situation because your safety devices in the group inlet would not work. It would work if you cut it in before the pump as you suggest but then you can't perform maintenance on the check valve in future because you can't isolate it.

I would alter the pipework by increasing the length of the longest pipe that is vertical, the flow into the pump and this would raise the pump, allowing you to get a check valve in the correct place. In the correct place the check valve could easily be isolated for replacement if it fails in the future.

The lack of a swept tee is not to Manufacturer's Instructions but in my opinion the restriction you have there by using a normal tee is negligible. Someone else may disagree on that so all opinions or corrections welcome.

 

[Stigster]

The good news about making these alterations is that the section that needs working on is able to be easily and completely isolated so the only water to escape would be the water inside the pump and the pipework between the isolating valves.

With the pump switched off, you can turn off the small red handle valve and the other small blue handle valve where the pipe comes out the floor. Then that part of the circuit is isolated. A wet vac or some sponges and towels would sort out the water escape when demounting everything.

 

[Scott_D]

Try closing the red handle valve and see if it fixes the temperature problem
Can you post some pictires of the rest of the cylinder?

 

[Best]

Get the plumber back to make final decision and carry out the work. Make sure plumber is G3 qualified for unvented work

 

[ShaunCorbs]

Get the plumber back to make final decision and carry out the work. Make sure plumber is G3 qualified for unvented work

by the looks dont think he was, well i dont know anyone in the trade that uses shark bite/ tectite fittings straight out of pump valves

 

[Best]

by the looks dont think he was, well i dont know anyone in the trade that uses shark bite/ tectite fittings straight out of pump valves

That's what I thought about the "plumber" and also saw the Tectite fittings which seem an odd choice and pointless. Although I do know of a few plumbers using same or similar. The OP I noticed mentioned the "I" word when talking about alterations to do. But I could be wrong

 

[Stigster]

I'm not going to argue that this shouldn't be looked at by someone with their G3 certification but on a side note, once that secondary return system is isolated from the cylinder by those easy to operate valves, is that part of the system still requiring G3 cert. to work upon it? Is it considered part of the unvented cylinder or is it simply part of the distribution system which anyone could work on?

I'm not trying to get around any rules (I have a valid BPEC unvented card) but at which point does a part of a system like this stop being under the legislation regarding unvented cylinders?

 

[ShaunCorbs]

I'm not going to argue that this should be looked at by someone with their G3 certification but on a side note, once that secondary return system is isolated from the cylinder by those easy to operate valves, is that part of the system still requiring G3 cert. to work upon it? Is it considered part of the unvented cylinder or is it simply part of the distribution system which anyone could work on?

I'm not trying to get around any rules (I have a valid BPEC unvented card) but at which point does a part of a system like this stop being under the legislation regarding unvented cylinders?

Would need to check if he's messed up any of the safety things

 

[Stigster]

Just to be clear in my last post I made a typo and my first sentence was supposed to say -

"I'm not going to argue that this shouldn't be looked at by someone with their G3 certification..."

For safety reasons as you rightly state. I was just wondering whether the secondary return isolated from the cylinder would need someone G3 certified to work upon it. I am not suggesting OP messes with the system themselves. If they wanted to change that 22mm compression tee for a swept tee, that is clearly part of the unvented system so should not be worked on by an unqualified person.