Unvented Cylinder Installation. Spot the Problem!

[Iceverge]

9 hours ago, Gav_P said:

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. 

Will do. 

[Nickfromwales]

Wow, just wow. 
 

G3 is in place for a reason. Having heard that a country that boasts better BRegs than old Blighty ignores such a thing is staggeringly bad news. 
Having followed this with ‘interest’ before replying, I have to say that I don’t think you have a bad plumber. He clearly has no idea about G3 compliance, but in honesty the UVC MI’s should have accompanied your cylinder and I’m pretty sure ( albeit assumed ) that they would have stipulated the criteria for a basically safe and compliant installation ( most of all in respect of D1 & D2 discharge particulars ) for him to have followed. 
However, you state that you wish to move in, so I will focus on your safety and that of your family;

The UVC has a T&PRV and it is now fitted to a poor but functional standard, ergo the UVC cannot get to a terminal failure condition, whereas in the first picture it certainly was a huge concern. Good news there, the plumbers remedial work is robust. 
 

The one thing missing right now is a 22mm non return valve on the hot output of the UVC. This will protect the cylinder against incorrect plumbing of the balanced arrangements prior to the feeds to it, including unregulated back flow from incorrectly plumbed mixer outlets. That NRV can be removed later, if further improvements are made, and ideally presented here for scrutiny, ( but it needs doing before you move in with the setup as-is ).
At that point you have a safe install. It’s not ideal now, but it’s not terrible, ( the first pic WAS terrible ), so you’re ok with it if you do the above amendment. 
These things do fail with quite spectacular results, so do not treat this like it’s just a leak or something simple that would go wrong....I’ve seen a few go and it’s usually resulted in a 5 figure insurance job ( if the G3 in UK was adhered to and the UVC was regularly inspected.)   
The correct valve for the EV is this Link so no excuses, get that changed too before you move in. 
The EV can be laid on its side, but the internal rubber diaphragm will have far reduced longevity if you leave it like that. Get it turned vertically ( with the feed at the bottom ) also, if you want the best for reliability. 
 

?

Edited February 19, 2021 by Nickfromwales

[Iceverge]

Morning All, 

 

Thanks very much for the help. I was thinking/worrying deep into the wee small hours this morning. I think I've come up with a solution, although with knowledge its a bigger problem than what I've shown you. For clarity the plumber has installed 16mm, 26mm and 32mm multilayer crimp fittings. 

 

Firstly we checked the EV and adjusted the pressure from 2.5 to 3.0 Bar to match the multibloc. 

 

8 hours ago, Nickfromwales said:

G3 is in place for a reason

I was beginning to think I was the only one who thought so! 

 

8 hours ago, Nickfromwales said:

the UVC MI’s should have accompanied your cylinder and I’m pretty sure ( albeit assumed ) that they would have stipulated the criteria for a basically safe and compliant installation

They did come with it and depict a normal G3 installation.  I also contacted the engineer at Joule and he insisted that the diagram be followed. Prior to the plumber returning to rectify I explained where and how to connect things as per the diagram. It didn't happen. 

 

8 hours ago, Nickfromwales said:

The one thing missing right now is a 22mm non return valve on the hot output of the UVC

I'll fit it today. 

 

8 hours ago, Nickfromwales said:

Get it turned vertically ( with the feed at the bottom ) also, if you want the best for reliability. 

I'll leave that off for now as I think I'm going to redo the cylinder installation myself in the coming months. I will take off the handle today. 

 

 

 

Ok on to the big problem. 

 

As I said above I initially asked  the Cold Mains to be taken to the UVC and everything to be distributed via a manifold system. This didn't happen. 

 

The plumber installed:

 

1. A Mains stop cock

2. A mains PRV

3. Teeed off the main pipe to provide cold for (downstairs) 1 basin mixer, 1 cistern and the kitchen tap. 

4. Routed the mains to the UVC

5. Teeed off for a cold manifold

6. Installed the UVC as shown. 

7. Routed the water to a hot manifold 

8.Teed off in 26mm pipe for the (downstairs) aforementioned basin and kitchen tap. 

9.Went from 26mm to 2x 16mm pipe for the final runs to the taps downstairs. 

 

Will this mean our basin and kitchen mixer will remain unbalanced even if we remedy the UVC installation?

 

Is this contributing to the 3.5 Litre and 1 minute wait time for hot water in our kitchen tap at full hot? ( I thought it was just the 26mm pipe run holding a lot of cold water) 

 

The basin takes ages to get hot too. 

 

 

My solution: 

 

Run more 16mm pipes from the UVC to join the final runs to the downstairs taps. 

 

Unfortunately this will require pulling down a ceiling in our utility and either cutting out a section of our built in utility cupboards that were installed last week or removing them. 

 

I'll add a video in a while and sketch a diagram. 

 

Thanks, 

Jonathan

 

 

 

 

 

[Iceverge]

[Iceverge]

Ok,

 

I've removed the handle to the EV.

 

I couldn't fit in the non return valve as I have no tools or fittings for the multilayer pipe and I would need to cut it and rejoin. 

 

I measured the kitchen tap's performance. 

 

It is a run of 11m from the UVC. Half 26mm, half 16mm. 

 

It takes an average of 45 seconds and 4 litres of water to get to full hot temperature. This seems very slow. The issue returns if you leave the tap alone and come back to it. 

 

Is it the unbalanced feeds that is causing this or an issue with the TMV?

 

 

 

[LA3222]

26mm for 5.5m is roughly 2.65l

16mm for 5.5m is roughly 1.11l

 

So your total dead leg is approx. 3.76l ( assuming my maths is correct!) 

 

That would tie in with your 4l, so it looks like ypu are simply pulling the dead leg through at 8.89l per minute flow rate.

 

 No issue with the TMV or balancing, just the distance from the tank to the tap causing the issue.

[Iceverge]

Groan.

 

So we're stuck with it? I was hoping for better. 

 

Can I install an under sink water heater on the hot water line to help this?

[Nickfromwales]

1 hour ago, Iceverge said:

Groan.

So we're stuck with it? I was hoping for better. 

If you can run 2x 12mm MLP to completely replace the 26mm > 2x16mm runs, that'll improve things a fair bit.

As above, everything is balanced as there is a PRedV at the stopcock location, so everything downstream of that is at the same potential.

[Iceverge]

It would be difficult. The pipes are behind utility and kitchen cabinets that went in last week.

 

Would 10mm Hep do 6L/minute at 3 bar over 11m for the kitchen taps. No elbows? 

 

 

[Nickfromwales]

3 hours ago, Iceverge said:

It would be difficult. The pipes are behind utility and kitchen cabinets that went in last week.

 

Would 10mm Hep do 6L/minute at 3 bar over 11m for the kitchen taps. No elbows? 

 

 

Kitchen tap on 10mm will be acceptable, but won’t jetwash the plates. Done that a few times so deffo will work. 

[Iceverge]

Ok, we're moving in the next few days so I'll see what it's like to live with. 

 

As above could I fit an undersink heater as a workaround? 45 secs seems super long to wait for hot water. 

[Onoff]

7 hours ago, Iceverge said:

Ok, we're moving in the next few days so I'll see what it's like to live with. 

 

As above could I fit an undersink heater as a workaround? 45 secs seems super long to wait for hot water. 

 

Tell me! Just whacked the bathroom basin mixer on hot and timed it. 1m to warm, 1m15s to hot ?

[Iceverge]

So we're in! 

 

The kitchen tap is taking 45 sec on average to get hot water. The downstairs basin 1 minute. 

 

In practice we're not waiting for water to heat up in the basin and in the kitchen we're dumping 20-30 litres a day waiting for the hot tap. With this drawing the equivalent amount of cold into the UVC. As I've set it up to heat all the water with a cheap night rate tariff this meant my 9pm shower went cold half way through.

 

With more accurate measuring I reckon its a total 16.2m of a hot water run to the kitchen tap. Compromised of 9m of 16mm(12mm internally) and 7.2m of 26mm. (20mm internally)

 

Doing the sums this gives 2.26l from the 26mm pipe and 1.02l from the 16mm pipe. Where is the remaining 1.22 litres of water coming from. Is it a delay through the TMV? 

 

The reason that this makes a difference is that if i was to change the setup to 16mm pipe all the way through it would speed up time to tap to 18 seconds  about 2 litres best case or 30 second worst case , still too slow.  Alternatively I go 10mm Hep20 and potentially have hot water in 5 seconds, with perhaps a lower flow rate than 6l/m we have currently. 

 

I'm tempted to just install an undersink water heater and cap the hot line off. We'd have very little hot water delay. No pipe losses and wouldn't have to go tearing down the ceiling of our lovely new house. 

 

The only negatives I can see would be less chance to avail of night rate electricity. The losses from storing water in a smaller volume would probably be offset by the lack of pipe losses. 

 

Your thoughts please. 

 

Jonathan 

 

 

 

[Nickfromwales]

Ouch. 
There is a cheap seats fix which will reduce these huge waiting times. Downside is you’ll need to heat hot water on demand by the sounds of things. 
You can fit a HRC ( hot return circuit ) pump at the UVC which just warms through the pipework in the plant room, so just pumping through all the local large bore stuff and back to the UVC. I can see a HRC tapping blanked off I think, so the facility is there. 
Heating the cylinder on E10 may be something that works better for you, as with the HRC being needed throughout the day you’ll need to keep the tank up to temp, and E10 will lend itself to you coordinating with that to minimise running costs.

If you have PV, then summertime costs should be significantly reduced. 
Thets the only way you can get a good overall outcome here, just a shame your designer didn’t ‘see this one coming’ and then “cajole” you into fitting a HRC ( eg to suggest an elegant solution for your ongoing comfort and practicality ).

Tye above solution would be cheap to implement, and will help out quite a bit as I think the biggest issue is the large dead leg in between the UVC and manifold. 

[Iceverge]

@Nickfromwales

 

I’m reluctant to fit a circulation pump due to the high energy losses. Also as we’ve built a passive house I'm worried about overheating issues in the summer. 

 

 Our only tariff option here in Ireland is 23:00-8:00 night rate (8c/kWh) or 24hr flat rate (13c/kWh). We have no PV fitted but plan to do so on the garage whenever that’s finished. 

 

I was the designer (a basic UVC and manifold layout with tips from this forum) but the plumber unfortunately ignored my drawings and instructions entirely and the manufacturers diagrams too. I wouldn’t have held much hope for them understanding or installing a return loop properly.

 

I’d prefer to reconfigure the entire UVC layout to minimise the dead legs by putting the TMV and Hot manifold as close as possible to the UVC outlet. Generally tidy up the layout and balance the cold manifold correctly. 

 

I think a 15l under sink water heater for the kitchen tap and downstairs basin would be the best solution to avoid removing fitted cupboards and taking down ceilings. Any reasons not to go down this route?

 

Jonathan

 

 

 

 

[TonyT]

You will need to run 2 dedicated power circuits for the point of use heaters.

 

wouldn’t a return circuit be worth reconsidering.

[Oz07]

Does anyone here use Hotun for a trapped tundish discharge? I had one fail on me recently the owner/inventor cam round, replaced and left me with a spare. Was good service but doesn't give too much faith when 6 months old

[Iceverge]

3 hours ago, TonyT said:

You will need to run 2 dedicated power circuits for the point of use heaters.

 

wouldn’t a return circuit be worth reconsidering.

There is already a fused spur under the sink for the dishwasher. 

 

Would a 2kw undersink water heater should run from this ok? ( I don't know if it's allowed but this was the setup in our rental house and it was both fast and economical to operate) 

 

https://www.plumbnation.co.uk/site/zip-aquapoint-iii-under-sink-unvented-15l-water-heater/

 

At the moment our daily cost of water heating is €1.70/ day. (€620/year)  I reckon this could expand by many multiplies if we were to install a hot loop as the hot circuit would be continually cooling the tank and we would have to pay double to run the immersion during the day. 

 

 

[Nickfromwales]

5 hours ago, Iceverge said:

 

I’d prefer to reconfigure the entire UVC layout to minimise the dead legs by putting the TMV and Hot manifold as close as possible to the UVC outlet. Generally tidy up the layout and balance the cold manifold correctly

That would remove about half a pint of dead water, probably less in actuality. 
What you could do is have the TMV hot inlet connected to the top of the UVC, with that going in on a 90o bend, so the mixed output of the TMV is rising vertically, and then have the hot manifold rising vertically off the TMV. That would promote natural convection into the TMV and manifold thus creating a setup that Pre-heats itself prior to hot water being drawn from the smaller, downstream pipes.

5 hours ago, Iceverge said:

 

I’m reluctant to fit a circulation pump due to the high energy losses. Also as we’ve built a passive house I'm worried about overheating issues in the summer

Not yet heard of high energy losers, or an UVC overheating a PH, as these are all design considerations when building such a dwelling ?. Jeremy Harris stated he had such problems, but that was with a very high temp thermal store, not an UVC. That’s the single and only instance I can recall, as is no comparison model here at all. 
If the HRC pump is only pumping around the airing cupboard then I see no such high losses occurring, as the cupboard will attain an ambient and the delta T between the pipes and their immediate surroundings will be negligible, ergo the transfer from A>B will be hugely stunted. Fit some seals to the A/C door to promote that environment being maintained and you’ll be fine. 
Work out what these heaters and extra plumbing / additional points of loss & failure will amount to, and reconsider. 
Yes, the option of using the multipoint heater will work, but why not just improve the UVC install and improve the whole of house scenario vs invest more / lose cupboard space, and the rest of the house gets zero benefit.....

The improved performance of the kitchen sink will exacerbate the issue in the rest of the house, and that would piss me off even more. 
2 choices, both require money. One solves one problem, the other improves the whole of house situation. 
I know what I’d be doing. 

[Nickfromwales]

Oh, and insulate the ? out of all the hot pipework and ancillaries too, of course. 

[Gav_P]

5 hours ago, Oz07 said:

Does anyone here use Hotun for a trapped tundish discharge? I had one fail on me recently the owner/inventor cam round, replaced and left me with a spare. Was good service but doesn't give too much faith when 6 months old

I’ve just fitted one... seems nice quality piece of kit, especially compared with a “standard” tundish.. but it should be at 3 or 4 times the price. 
 

How did yours fail?

Edited February 28, 2021 by Gav_P

[Iceverge]

50 minutes ago, Nickfromwales said:

That would remove about half a pint of dead water, probably less in actuality. 

I was reckoning about 400ml so you're pretty much spot on! ( about 4 seconds at the kitchen tap, 6 seconds at the basin) The very best case I can get water to the kitchen tap in a 16mm pipe is 16 seconds. I'm tempted by having hot water at the kitchen tap in less than 1 second with the undersink heater and 4 seconds at the basin tap. 

 

55 minutes ago, Nickfromwales said:

What you could do is have the TMV hot inlet connected to the top of the UVC, with that going in on a 90o bend, so the mixed output of the TMV is rising vertically, and then have the hot manifold rising vertically off the TMV

 

Top plan. 

 

1 hour ago, Nickfromwales said:

Not yet heard of high energy losers, or an UVC overheating a PH, as these are all design considerations when building such a dwelling

Me neither, I have heard about one other instance of a thermal store causing overheating. The trouble is that given most houses have such high losses and high heating demands that 100w here or there isn't even noticeable so nobody really bothers designing it in. 

 

https://passivehouseplus.ie/magazine/new-build/ecological-lake-district-passive-house-generates-its-own-electricity

 

1 hour ago, Nickfromwales said:

If the HRC pump is only pumping around the airing cupboard then I see no such high losses occurring, as the cupboard will attain an ambient and the delta T between the pipes and their immediate surroundings will be negligible, ergo the transfer from A>B will be hugely stunted. Fit some seals to the A/C door to promote that environment being maintained and you’ll be fine.

 

It will remove a reasonable chunk of my dead leg problem for sure but the issue of the remaining 7.2m of 26mm pipe now hidden in the ceiling and behind the cupboards would remain.

 

I suspect I would still be left with a 30 second time to hot at the kitchen tap for all the extra effort. 

 

1 hour ago, Nickfromwales said:

Work out what these heaters and extra plumbing / additional points of loss & failure will amount to, and reconsider. 
Yes, the option of using the multipoint heater will work, but why not just improve the UVC install and improve the whole of house scenario vs invest more / lose cupboard space, and the rest of the house gets zero benefit.....

The improved performance of the kitchen sink will exacerbate the issue in the rest of the house, and that would piss me off even more. 
2 choices, both require money. One solves one problem, the other improves the whole of house situation. 
I know what I’d be doing. 

 

 

If we were back at square 1 I would plumb the whole thing myself. I would trial 10mm to the kitchen tap during construction to see if the flow was sufficient. If not I would upgrade to 15mm and see if the time to hot was quick enough. If neither was enough I would consider an instant water heater to boost the kitchen tap or else maybe a circulation loop. Sadly that ship has sailed.  

 

To go down this route now would require core drilling through a 225mm concete first floor, taking down the ceiling of our utility. Cutting out the back of one of the cupboards in the utility, painstakingly threading the required pipe under the units in the utility, the W/C and the kitchen. and replacing/repairing everything once we're done. On top I would have to attack the UVC installation and replace multilayer pipes with something I could DIY. All for a potential reduction from 45seconds to a best case of 16. (assuming 10mm pipe won't provide 6l/m) 

 

The rest of the house is ok as all other outlets are fed from 16mm feeds via very short runs. The shortness of the runs hides the large volume pipes upstream of the manifold. 

 

I will probably take on the work myself at this stage as my faith in plumbers is low. In fairness the builder agreed to pick up the costs so I'm not massively hung up on the materials bill. 

 

 

 

[Oz07]

22 minutes ago, Gav_P said:

I’ve just fitted one... seems nice quality piece of kit, especially compared with a “standard” tundish.. but it should be at 3 or 4 times the price. 
 

How did yours fail?

Not sure. Quite a bit of detritus in there from plumber soldering above. One day I went to bed and that whole half of the house stunk of drains. I tipped a touch of water in there regularly till replaced and it made a seal good enough to stop odour. He took it away to examine. Helpful guy really

[Oz07]

Also @Gav_P No need to encourage price increases!

[Gav_P]

20 minutes ago, Oz07 said:

Not sure. Quite a bit of detritus in there from plumber soldering above. One day I went to bed and that whole half of the house stunk of drains. I tipped a touch of water in there regularly till replaced and it made a seal good enough to stop odour. He took it away to examine. Helpful guy really

There is only the spring and the flap/disc that moves, I assume it was that part that had failed if it was letting smells in. 
 

26 minutes ago, Oz07 said:

Also @Gav_P No need to encourage price increases!

I didn’t think I was... I said it should be good quality as it’s 3 or 4 times the price of other tundishs.