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pspec

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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.

bGv9i1.jpg


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..

J3Z0E1.jpg


sJfkrd.jpg



O8xCyA.jpg


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
 
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.
 
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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.
 
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?
 
Get the plumber back to make final decision and carry out the work. Make sure plumber is G3 qualified for unvented work
 
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
 
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
 
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?
 
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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
 
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.
 
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Thanks for all the input guys I think I’m going to do a bit of everything.


I did the experiment that scott_d suggested as a conformation the water was flowing backwards and here’s the results..


Kitchen tap ran for 5mins with red and blue taps open gave a temp of 39C

Next day turned off red and blue taps to insure no back flow of water

Ran tap for 30sec water was 50C after 2mins water was 61C continued to run tap and temp stayed at 61C

With open red and blue taps and pump turned on the temp went to 69C.


So still a small climb from 61c to 69c but considering the difference was 39c to 69c I’ll call that a fix….


I’m going to insert the valve as Stigster suggested but I am tempted for speed just to pop it behind the pump on that horizontal pipe…


So that all being said something else came to light (I say came to light it has happened before but I’d forgotten about it) the fuse on the tank had tripped so the boiler had being heating up with the power of magic….and there I thought magic doesn’t exist ……

I think it must have blown 4 or 5 weeks ago as I would normally get with small gaps between them 3 to 4 shower. But the last 4 to 5 weeks I’ve been getting 1.5 to 2 showers still not bad considering nothing is heating the water..

So the power of magic has been heating my water … cool I wonder how much per unit magic costs ;)


Why not let’s insert another photo………..

Wpm0KZ.jpg

WTLGHa.jpg


I keep the electric heater turned off so all heat comes from the oil boiler downstairs and outside.


This is what I think is happening……………..


The downstairs boiler (not mains pressure old tank in roof type) is very basic a timer clock turns it on from 6am until 10am and all it does is constantly heat the water in the heat exchanger it kicks off and on to keep the 500ml of water in the exchanger at the set temp. If the pump upstairs draws water to heat the hot water tank it continues to heat the water if the upstairs pump is off it just heats the 500ml in the exchanger…

So with the fuse blown the pump doesn’t come on so no hot water is circulated to the upstairs hot water tank.

So this is where the mystery lies, there is no water circulating from boiler the electric heater is off but I have hot water……….. Quick call Ghostbusters….


No but really I think as heat rises the hot water from the heat exchanger must slowly start to rise which must then in turn switch the boiler on which creates more heat which then rises that starts a loop of boiler on small amount heat rises boiler on small amount of heat rises and this small loop cycle must be heating the tank not to full capacity but enough for a shower …

One thing a have noticed (see photo above) the two pipes that go into heat the tank the top one is always hot (not scolding hot) between the boiler on times 6am to 10am and the bottom pipe always cold that’s with the tripped fuse (no pump running). I’ve now reset the fuse so pump is running and both pipes are scolding hot.

So what do you think could this be some sort of capillary action (I think that’s the term) and does that mean I have a missing check valve on those pipes as surly it should only heat when you want it to..

Or is it the magic leprechauns heating my water for freeeeeeeeeeeee …….please be the leprechauns..

.
 
Just a minor thought and nothing to do with your problem but does the pump run 24/7 ? and does it need to, if not get it wired into its own time control The pump for your hot water circuit (yellow one)
 
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This is like some exercise set to apprentices. "How many examples of bad practice and poor workmanship can you identify in this system?"

I'll start the list with:

1. The circulation pump that is 'secured' in place with string.

IMO, whoever installed that system is clueless. It needs to be taken to pieces and redone properly by someone with the appropriate skill, a G3 ticket and an ounce of professional pride.

Also, pspec, unless you are a qualified plumber with a G3 ticket, which I doubt, you should not be attempting DIY repairs and modifications. Unvented systems are dangerous if they are not done right.
 
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Just a minor thought and nothing to do with your problem but does the pump run 24/7 ? and does it need to, if not get it wired into its own time control


no not 24/7 its somehow wired to the down stairs outside boiler time clock so only on when the boiler is. From what I've been told it's incorrectly wired as it's meant to be wired to the house ring with independent time clock as you suggested so it can be utilised when needed not just when the boiler is on...

not sure who did the plumbing or wiring but they need a kick in the pants..
 
This is like some exercise set to apprentices. "How many examples of bad practice and poor workmanship can you identify in this system?"

I'll start the list with:

1. The circulation pump that is 'secured' in place with string.

IMO, whoever installed that system is clueless. It needs to be taken to pieces and redone properly by someone with the appropriate skil, l a G3 ticket and an ounce of professional pride.


if it wasn't mine I would laugh but it is so I wont..

he must of run out of clamps he use one just below the pump then I can only presume he went to the pub...
 
The Temperature & Pressure relief (T&P) valve is piped up in plastic which is a big no no. Please for the love of all that is holy, tell me that the pipe reappearing round the back of the cylinder is not the same T&P discharge pipe? It is of a non-compliant material, it's too long, falls and rises again and God knows where it terminates.

I really want to see the Group inlet/Combination valve on the cold feed into this cylinder. Please tell me that there is one at least!

This job looks like it was done by a bloke I know, known in the local area as "Tectite Tony".
 
The Temperature & Pressure relief (T&P) valve is piped up in plastic which is a big no no. Please for the love of all that is holy, tell me that the pipe reappearing round the back of the cylinder is not the same T&P discharge pipe? It is of a non-compliant material, it's too long, falls and rises again and God knows where it terminates.

I really want to see the Group inlet/Combination valve on the cold feed into this cylinder. Please tell me that there is one at least!

This job looks like it was done by a bloke I know, known in the local area as "Tectite Tony".

Would say there isn't one unless it's above the cylinder
 
The plumber must have charged a fortune for materials... tectite fittings ain't cheap especially 22mm size, I also like the clip screwed into the dimplex cylinder ... it's a sign of someone just holds the ticket but ignores all regs and hasn't got a clue or someone not G3 at all.

As many engineers advised already you should get back to the installer to let him sort it only if he's G3 if not look for Simone who is
 
Is there a tundish - and if so, where? It must be clearly visible and within 600mm of the T&P relief valve.
That job is DIY looking and in fact probably could have been done (albeit illegally) better by a competent diyer who actually reads and tries to adhere to the basic MIs.
I am fearing the worst about the discharge pipe diameter size, materials and how it terminates.
That install needs a qualified decent plumber to remove it all and start again with most of the plumbing. No point in talking about the owner messing about with one minor problem. If this has been recently installed by someone claiming to be a plumber, then sue them
 
Is there a tundish - and if so, where? It must be clearly visible and within 600mm of the T&P relief valve.
That job is DIY looking and in fact probably could have been done (albeit illegally) better by a competent diyer who actually reads and tries to adhere to the basic MIs.
I am fearing the worst about the discharge pipe diameter size, materials and how it terminates.
That install needs a qualified decent plumber to remove it all and start again with most of the plumbing. No point in talking about the owner messing about with one minor problem. If this has been recently installed by someone claiming to be a plumber, then sue them
Tell us what you really think mate :p:p:p:p
 
You shouldn't be playing with this it comes under G3 of building regs and should only be worked on by a registered engineer whether installing or maintaining, it looks like a new install so you should also have got a certificate for building regs notification for the work, you need the get the installer back assuming he/she is G3 certified if not employ someone who is, don't want to over dramatise but if not installed you could create an explosive situation
 
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