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Unvented Cylinder Installation. Spot the Problem!


Iceverge
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Hi All,

 

The plumbers put in our UVC cylinder yesterday. I have raised a few things I spotted with the main contractor and he was getting in contact with the plumber.

 

Could those of you with more experienced eyes please have a glance at my picture and let me know anything else that needs to be rectified. 

 

 

What I've noticed/questioned. 

 

 

1. There is no tundish fitted and the over temp valve discharges via some 16mm pipework over a long distance to a hidden pipe into the main waste water system. 

 

2. Does the tank require an overpressure valve on the cold feed? There is one on the cold main entering the house. 

 

3. Does the tank require a thermostatic mixing valve? 

 

4. Is it safe to have a switchable valve on the expansion vessel?

 

 

Thanks in advance. 

 

Over temp Discharge.jpg

Tank installation.jpg

Tank model.jpg

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1. Pipework is too small and doesn’t follow the MIs or BRegs, tundish is mandatory. 

2. Yes - the MIs require a Control block with over pressure relief. 
3. Depends on tank temperature. If not the bath must have one to have water below 46°C

4. No - that is in the wrong place and must be removed


And all of the exposed pipework should be insulated. 

 

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Thanks @PeterW

 

We are in Ireland and believe it or not Bregs are silent on this. I can imagine that'll only change when there's an accident. 

 

1. The discharge pipework into the main wastewater pipework. Will it need a trap to prevent smells or is this not allowed? 

2. Understood

3. Would thermostatic mixers for the bath count? I want to have the option of storing water at the max tank temp anyway so I'll insist if only to keep the basins safe. 

4. Understood. 

 

I'll get him to insulate. 

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Shouldn't the expansion vessel be upright?  I have never seen one on it's side before.

 

And when the plumber comes back get him to sign the comissioning sheet for the cylinder, both to validate the cylinder warranty and for building control to see.

 

Though I am not sure I trust this particular plumber to know how to do it properly, he clearly can't read some simple instructions.

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The building control in Ireland is done by the design professional e.g. Architect/engineer. The process is less than rigorous and the hazards of incorrectly installed UVC's are not widely understood. 

 

I spoke to the manufacturer and he's OK with the expansion arrangement however I'll at least get them to take the handle off it. He was ok with the over temp line dimensions and length too but I can't see any reason not to redo it as per MIs when the tundish is being fitted. 

 

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  • 3 weeks later...

Can I Bump this please to anybody who knows better?

 

@PeterW  maybe. 

 

Also what is an acceptable amount of cold water to dump before hot reaches the kitchen tap?  It is 11m total pipe length to the tank. 

 

I will measure teh time and volume it in the morning when the system is cold but it took much longer than I thought to get hot water today when I first tried it. 

 

Thanks, 

 

Jonathan 

 

 

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Balancing is wrong ... why has he balanced the mixing valve only, not the full cold ..? 
 

That will exacerbate your flow to a kitchen mixer as the cold pressure is higher than the hot. 
 

4E97C103-9F51-4C0C-9ED3-FE89074F391D.thumb.jpeg.74f6654afa51a6440a00cda12b0889b2.jpeg
 

tee should be gone before the control block, and cold feeds should be tee’d in where I put the blue line 

 

Also, he’s done a decent job on the relief valves but that open pipe will smell. Should have a HepVO on it or similar. 

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6 minutes ago, PeterW said:

Balancing is wrong ... why has he balanced the mixing valve only, not the full cold ..

 

I don't know. I suspect it's probably the same reason that 2 out of 5 taps we have are connected backwards. 

 

I had asked the builder to direct the plumber to insert the valve at the location of the Tee. Would this have been right?

 

The build it through a main contractor. So every point I try to make is lost in translation. Its very frustrating. I'm kicking myself for not plumbing the house myself in Hep2o. 

 

 

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As long as the cold feeds come after the control block then the system would be balanced. The issue as it stands is that cold is drawn to the manifold before the control block (I'm no pro - 'learnt' what little I know on here!). 

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That makes sense, 

 

However I believe the main pressure reducing valve is set to 2.5 bar from looking at the gauge. 

 

The control block is factory set to 3 bar. Would this mean that as long as my main pressure reducing valve is set below 3 bar it would still be balanced? 

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Is that an isolation valve before the EV? I don’t think you can do this (just in case someone closes it). 

You can have a service lock valve though. 
 

oh... and can you get at the valve on the other end of the EV to check the pressure? It looks very close to the wall

D6484FC4-B94B-4056-A344-01CD76B0D9CC.jpeg

Edited by Gav_P
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5 minutes ago, Iceverge said:

@Gav_P Yes, it is. I asked for the handle to be removed but alas............... 

 

Here is another view of the expansion. Will 100mm be enough?

 

image.png.73246d231bffd494e796021b99cabd35.png

Yeah 100mm is plenty. Just need to get a pump on the valve (like a car tyre pump). 
 

I would definitely get that ball valve removed, or ideally replaced with a service lock. If it gets shut by accident then water will be pissing out the pressure relief valve every time the o heats up. 

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Just now, Gav_P said:

Yeah 100mm is plenty. Just need to get a pump on the valve (like a car tyre pump). 
 

I would definitely get that ball valve removed, or ideally replaced with a service lock. If it gets shut by accident then water will be pissing out the pressure relief valve every time the o heats up. 

Worst case you could put something like a jubilee clip on it to stop casual / accidental closure. 

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33 minutes ago, Gav_P said:

Worst case you could put something like a jubilee clip on it to stop casual / accidental closure. 

 

Good plan. I could rectify the issues myself but I feel like it's not my job. Unfortunately it usually ends up being my job. 

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I noticed in the kit there was a separate tank thermostat for controlling the immersions. They immersions have an inbuilt stat. Will this be enough or should the plumber have installed it? 

 

Edited by Iceverge
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50 minutes ago, Gav_P said:

 

I would definitely get that ball valve removed, or ideally replaced with a service lock. If it gets shut by accident then water will be pissing out the pressure relief valve every time the o heats up. 

 

I'd just leave the valve in the open position then undo the nut and remove the handle. Loosely put the nut back on and tie the handle somewhere local on a bit of string/small cable tie. 

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12 minutes ago, Iceverge said:

I think I'll do that. Would the system work as is apart from that? 

 

We were hoping to move at the weekend.

I can’t see why it wouldn’t .

Has the plumber not commissioned it yet then? 

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43 minutes ago, Gav_P said:

I can’t see why it wouldn’t .

Has the plumber not commissioned it yet then? 

Commissioning was never mentioned. There's no G3 signoff required in Ireland. There probably should be looking at what's happened. 

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16 minutes ago, Iceverge said:

Commissioning was never mentioned. There's no G3 signoff required in Ireland. There probably should be looking at what's happened. 

Ah well in that case. You better check the EV is at the right pressure (usually 3 bar same as the control block, but maybe yours is 2.5?), and make sure both the T and P valves operate. 

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