Unvented Cylinder Installation. Spot the Problem!

[Nickfromwales]

44 minutes ago, Iceverge said:

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. 

 

 

Top plan. 

 

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

 

 

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. 

 

 

 

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. 

 

 

 

Hmmm......I feel your pain. My 2 penneth, is get in there, tackle it now, and live a long and prosperous life full of instantly available hot water.

I suppose you'd have loved it if your plumber cajoled you into fitting an HRC, but hey ho. If the builder will sort the materials, then bite the bullet and go for it. Remember the delivery AND the return pipes will both need uber-insulating with the best amount you can get onto them. Neoprene gives good values if space ( diameter ) is tight.

[Oz07]

Sorry @Gav_P thought you meant the reverse. 

 

It's next to my heating manifold with 65c temp or something like that. I suspect the heat warped the rubber. I think if my new one fails he will have to put some disclaimer in the instructions about placing near heat sources. 

Edited February 28, 2021 by Oz07

[Gav_P]

50 minutes ago, Oz07 said:

Sorry @Gav_P thought you meant the reverse. 

 

It's next to my heating manifold with 65c temp or something like that. I suspect the heat warped the rubber. I think if my new one fails he will have to put some disclaimer in the instructions about placing near heat sources. 

That’s crap if it’s really the reason for failing. The radiant heat from heating manifold shouldn’t do that should it? Considering it’s designed to be on part of a vent system that could see 90-95+*c. 
 

Still, either way, it’s great customer service! Will be interested in what the route cause is. 

[Gav_P]

1 hour ago, Nickfromwales said:

My 2 penneth, is get in there, tackle it now, and live a long and prosperous life full of instantly available hot water.

I’d do this too... better off doing it correctly now, rather than a solution that will always feel like a sticking plaster. 

[Iceverge]

Thanks for the inputs. 

 

No time to do anything at the moment so I'll mull it over. 

 

I'll let you know when I go further. 

[Iceverge]

Right, I'm back at this eventually. I've spoken to the builder and he's happy for me to take it on (at his cost) and plumbers are impossible to come by at the moment in Ireland, not to mind ones who will actually follow MI's and Bregs. 

 

I've made a sketch of my proposed layout for the UVC and Manifold. 

 

Can peeps with more knowledge please have a quick look and critique please. Maybe @Nickfromwales and @PeterW.

 

I've opted to use 10mm for the kitchen tap as the run is 13m. A reduced flow will be the trade off for a speedy delivery of hot water I hope. I'm opting to remove a separate pressure reducing valve as I hope the Multibloc will do all. 

 

As I'll need to run new pipes downstairs ( with the associated hacking of our new ceiling) I'll be using a branch layout for the kitchen and downstairs WC and a radial layout elsewhere. 

 

Have at it!!!

 

 

 

Plumbing.pdf

Edited November 12, 2021 by Iceverge
I spotted an error in the diagram

[PeterW]

@Iceverge do the WC feeds in 10mm

[Iceverge]

9 minutes ago, PeterW said:

@Iceverge do the WC feeds in 10mm

 

Sorry I didn't mention. 

 

I'll be joining into existing 16mm pipe for a everything except the new pipes to the kitchen and WC downstairs. I could run 10mm but it would only be for the first 2m to join to the old pipes. 

 

Also all our toilets have these throttleable valves fitted. Will this override the need for 10mm pipe to the cisterns?

Edited November 12, 2021 by Iceverge

[Dan F]

It's hard to comment without more information. What flow rates are you designing for? Are you planning to use copper, or plastic off of the manifolds? How long are the 15mm runs to the showers?    Using a manifold and micro-bore pipes to avoid a hot recirculation loop is a good idea but, in my opinion, to be sure you get it right you really need to look at each run and the veolcity and pressure loss, based on design flow rates, be be sure you are using the correct pipes. 

[Iceverge]

47 minutes ago, Dan F said:

It's hard to comment without more information. What flow rates are you designing for? Are you planning to use copper, or plastic off of the manifolds? How long are the 15mm runs to the showers?    Using a manifold and micro-bore pipes to avoid a hot recirculation loop is a good idea but, in my opinion, to be sure you get it right you really need to look at each run and the veolcity and pressure loss, based on design flow rates, be be sure you are using the correct pipes. 

 

It's a remedial situation so I'm stuck with 16mm multilayer pipe for 90% of the runs from the manifold.

 

It's the layout of the UVC I wanted to be sure of. I'll be using Hep2o everywhere until i connect to the 16mm pipe. 

 

Everything is 10l/min except the basins which are 4l/min and the cisterns will be throttled to be quieter at terminus anyway. 

[Nickfromwales]

2 hours ago, Iceverge said:

Also all our toilets have these throttleable valves fitted. Will this override the need for 10mm pipe to the cisterns?

?

Why are you fitting those monstrosities? They’re isolation valves not flow restrictors btw.  
Any form of throttle there will result in lots of noise when the strangled flow is squeezing past that valve.
You want the WCs to fill as fast and  as quietly as possible so get rid of those from your plans ASAP. Most modern cisterns will already be restricted flow by manufacture, so should be unnecessary there. 
You ‘can’ do the WC’s in 10mm but 15mm is fine if that’s what’s there already. 

[Iceverge]

6 minutes ago, Nickfromwales said:

Why are you fitting those monstrosities? They’re isolation valves not flow restrictors btw.  

 

They're already fitted. I have no idea why, I assume because they came in the box with the toilet, although that didn't stop the plumbers chucking every other part I supplied. 

 

"it wasn't in the box mate"

"Funny that cause I just found it in the skip"   

 

Anyway I've been fiddling and neither open fully or throttled fully seems to be the quietest.

Riddle me that batman. ( Should that be Bathman  ???? !!) 

 

 

Also because I'm edging closer to ripping the house apart have you any objections to my diagram? 

 

 

 

 

 

 

[Dan F]

4 hours ago, Iceverge said:

It's a remedial situation so I'm stuck with 16mm multilayer pipe for 90% of the runs from the manifold.

Whas the kitchen then; 16mm MLP,  10mm copper or 10mm hep2o?

[Iceverge]

7 minutes ago, Dan F said:

Whas the kitchen then; 16mm MLP,  10mm copper or 10mm hep2o?

 

I have it detailed in earlier posts. 26mm to a manifold then 16mm the remaining distance. All multilayer. 

[Dan F]

1 minute ago, Iceverge said:

I have it detailed in earlier posts. 26mm to a manifold then 16mm the remaining distance. All multilayer. 

 

OK, thought I saw you said "I've opted to use 10mm for the kitchen tap as the run is 13m" 6hrs ago.

[Iceverge]

Sorry, I  think we're crossing wires here. 

 

The house wasn't plumbed very well by the plumbers. I'm attempting to fix it. the original was 26mm and 16mm MLP to the kitchen tap. I intend to replace it with 10mm Hep2o. 

 

Do you think my layout for the UVC is ok? 

 

 

 

[Dan F]

29 minutes ago, Iceverge said:

Sorry, I  think we're crossing wires here. 

 

The house wasn't plumbed very well by the plumbers. I'm attempting to fix it. the original was 26mm and 16mm MLP to the kitchen tap. I intend to replace it with 10mm Hep2o. 

 

Do you think my layout for the UVC is ok? 

 

Got it.  I'm not a plumber or UVC expert,  I did design all the pipe runs based on flow rates and lengths for our house though (in order to avoid a recirculation loop) which is why I was picking up on these elements.

 

10mm hep2o has a ID of 6.7mm, so what does this mean:

- volume of pipe is 458ml, giving you hot water in 2.8 seconds if you run at 10l/min, which is good.

- the design flow rate of 10l/min gives you a velocity of 4.7m/s.  Plastic pipes are good at bit more than copper (copper is max 2.5m/s), but 4.7m/s is very high even for plastic. (The hep2o spefification charts go up to 3m/s)

- the pressure loss over 13m at 10l/min (with no fittings) is 8.5bar, so the 4.7m/s isn't going to happen anyway!

 

That said, you should probably be able to get 4-5l/s, but why wouldn't you go up one size or add a 10mm hot return?   (a 10mm hot return on a single outlet is nowhere near as bad as running a larger hot return around the whole house)

 

With 15mm hep2o the hot water wait time would be 7.8s at 10l/min and you could run at 10l/min with velocity of 1.7m/3 and only 0.5bar pressure drop.  This seems like a better option unless you want to find something in 12mm and try to hit the sweet spot.

 

Edited November 12, 2021 by Dan F

[Iceverge]

I tackled this last week. 

 

A lot of time with a pipe cutters chopping out all the old mlcp and replacing it with new Hep2o. I have a bucket of brass crimp fittings and two bin bags full of 9 month old pipes to show for my troubles. 

 

I asked the plumbers initially to plumb the house, direct UVC and DHW only as we have no wet CH. I wanted a manifold radial system with no pipe joints unless absolutely unavoidable and then to have them in accessible places like under sinks or in the hot press (Airing cupboard for the non hiberno-anglophonics amoungst you.) The result was less than satisfactory, initially with an unsafe UVC installation, followed with a less unsafe UVC installation after rectification (still not right however) and a very slow delivery of hot water to the downstairs kitchen tap and WC. 

 

Other mistakes happened including installing the bathtub,  2 shower trays + a toilet, loosing lots of expensive parts (toilet hinges at €75 a set), leaving half the taps rigged up backwards and dripping at joints and burying MCLP brass fittings in lots of inaccessible locations. Then charging €6k+VAT (via the builder)

 

It's taken me the best part of a year to calm down! 

 

Anyhou here is the end result of the UVC layout Before and After. I've tried to follow my diagram I drew up in an earlier post. The "After" photo was taken before I was quite finished so ( no insulation, 2 pipes left to run), but please comment on any mistakes you can see. 

 

 

The other part I tackled was running balanced cold and a new hot water pipe to the kitchen tap. 

 

Previously it took 3.5 to 4 litres of cold flow ( about 35 seconds ) to get hot water at the kitchen tap. That was with the TMV already heated up from using another tap. The plumbers put 26mm MLCP to a manifold,  buried behind some built in units and then ran 16mm to the tap. I put the TMV directly onto the tank with the manifold (as per @Nickfromwales the top tip ) on top as the second photo shows. I then poked a hole in the ceiling of our utility and ran the pipes behind the utility cupboards and under the kitchen units to the tap. Total distance 12.8m.  (I marked the pipe to check).

 

The end result was a wait time of 9 seconds from totally cold to totally hot at the kitchen tap. I was chuffed! Interestingly a good chunk of the water volume needed to pass through seems to be in the tap itself. Flow rate is between 5.2l/min compared to the cold in 15mm Hep2o at 8l/min. It is more than adequate. If you want, you can still have 10l/min. Just blend it from hot to very warm at the sink using the tap mixer. The cold has the same distance to run but not through the TMV which I gather looses a lot of pressure. I think the tap itself and flexi tails account for much of the restriction to flow, even over a long distance.

 

I'm very pleased with the result.

 

There were some lessons learnt along the way. 

 

 

1. Hep20 is a excellent system. So long as you don't scratch the pipe it's idiot proof. My preschooler was able to make a connection. (Only 10mm thought, lol!) 

 

The fittings+stainless steel liners have a generous inner diameter compared to the MCLP brass fittings.

 

Hep2o 10mm@5.95mm, 15mm@10.25mm 22mm@16.90mm compared to the

MCLP  16mm@7.2mm 26mm@15.1mm and 32mm@19.4mm. (Plastic MCLP is even smaller)

 

The only exception was these. I would only use if really necessary. 

 

2. I tried to seal brass threaded fittings using only PTFE tape and had 6 very disappointing leaks. I dismantled it all again and discovered something called hemp and Boss White via the builders merchants. A little tricky at first and required roughening the brass thread to get the hemp to stick ( peel it like a apple with a hacksaw blade he said!). However I had a 100% hit rate on all my brass to brass connections there after. 

 

3. I had a leak from the expansion vessel where the 3/4" pipe tail cut through he rubber washer on the 3/4" tap connector I used. Lesson learnt. To be replaced by a Hep2o to 3/4" brass connector. 

 

 

Thanks to all the help on this thread especially @Nickfromwales and @PeterW. Now just to repair the ceiling! 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Edited December 5, 2021 by Iceverge

[ProDave]

Another sealant I use is Water Hawk Potable water jointing compound

[Onoff]

Big fan of Jet Blue Plus compound on brass fittings. Suitable in potable fittings too.