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TMV... How many and where ..?


PeterW

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So I've been looking at layouts and pretty much set now on having a 300 litre UVC as the main DHW supply for the house. 

This will be heated to 50 ish by the ASHP with an overnight kick once a week with the immersion to 65 for the legionnaires cycle.

It will also be the dump for the solar PV - I expect in summer given the tank immersion will be at 65 ish then the hot will be very hot !

Question is - TMV, where and how many ..?

Ensuite has the bath and shower, bathroom only has a shower (long story), downstairs wc and then there is kitchen and utility. Everything is designed for short pipe runs, with the  longest being 8m to the bath. 

So do I ...

- reduce everything to 43c at the UVC with one TMV

- install two TMV set to 43 / 50 respectively and feed the kitchen and utility from the hotter one

- do nothing and warn everyone the water is hot ..?!

Plan is mixers everywhere with potentially a 3 way shower valve with bath filler in the Ensuite 

thoughts ..?  

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One tmv on the hot outlet of the uvc set to 50oC to allow for any loss between cylinder and kitchen / utility, and then I'd feed a basin-only manifold with a secondary tmv set to 46oc ( "unassisted" doc M recommendation ). 

image.jpeg

If you zoom in you'll see cold manifold on the left, a primary tmv ( grey cap ) set to 50/51o C ) feeding a 6 way 'full range hot' manifold, and then a secondary tmv ( blue cap ) set to the lower ( user definable ) temp for the wash hand basins only ( in this case 4 in No; and fed with 10mm pipe to reduce wait time for premium temp water to reach the tap. 

Given hindsight I'd have fed the secondary tmv directly off the hot outlet to reduce the dead leg before it ( 28mm to the primary tmv ) but was against the clock there ( as I had to make that airing cupboard before I could fit the tanks! ) 

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They're all Hepworth. I supplied the materials with the customer paying direct in their own name ( so they could claim the vat ). I used my local supplier and he delivered to site for £100 ( fuel cost ) plus £100 cash bribe for the van driver which I paid as we needed them before the due date ( as no SE could be found to give me a sign off for my proposal to put that lot in the generous ( wasted ) attic space ( as per my original quote ) where the MVHR also resided. Behind that lot was the utility with a Vaillant gas boiler serving that TS. PV was mentioned but not there at the time so I recommended gas due to the remit being 3 showers run in unison, without compromise, hence the accumulator. 

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I've not seen an all plastic one with water controls / attenuation built in, just the plastic spurs. I used the hep ones so I could bring services into play as and when they were second fixed, and to make the concealed ( semi pedestal basins ) remotely isolatable so you never need to get 'to' the connections underneath. Made the terminations so much easier, 10mm hep into a 10x15mm spigot reducer and then the flexi fixed directly to that. Without the individual isolations you can't make the manifold live until every pipe is connected, tested, purged clear and cap-ended. A right pita when second fixing 4 bathrooms, a kitchen, utility, etc as you'd be continually draining down the lot, connecting and testing the next added circuit and repeating. There was another 2-port manifold fitted there afterwards for the non softned water which fed the chilled drinking tap at the kitchen sink, ( which also had the outside tap teed off it ), and the central heating filling loop. 

I'm not familiar with Tiemme and couldn't see anything similar from a quick search of their website. I used Hepworth ( and a couple of JG fittings on that job Hepworth weren't available same day from the local supplier so needs must ) as exclusively as I could on that job as they're very well made bits of kit and the Hepworth fittings are bullet and bomb proof. I also like the slimline stainless steel inserts which don't impact on the internal bore diameter as much as the likes of JG do. 

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15mm to everything else, basin hots and colds and colds to WC's in 10mm. 

If a tap is used / opened for a reasonable duration then it's not so problematic tbh. It's things like quickly washing your hands after visiting the loo that qualifies for scrutiny and as little dead volume as possible. Kitchen sinks / baths / showers etc tend to be run and left on, and at much higher L/p/min so the dead leg of cold is drawn out much faster. Basin taps tend to be very low flow rate so need consideration the most. 

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WCs will be on 15mm rainwater feeds - 4,000 litres of storage under the driveway ! 

Happy with the rest on 10mm - just looked again and saw your 15-10 reducers on the manifolds.

I had considered 22mm to the bath/shower mixer but still not convinced as I've got a 15mm feed to a rainwater shower currently and it easily copes.

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I'll just make 2 comments, Peter.

1 - Think about including a SureStop lightswitch style water cutoff, to make it easy when you go out / away in winter.

2 - If you are doing a shower room in your bungalow conversion, make sure it is the one downstairs (already done?). The people who did the conversion here put the bathroom downstairs, so we will need to replace it when the prospect of mum needing to stay downstairs only happens in a few years.

I plan to steel some insights from new generation Hiltons - cascade shower head in one side and a separate shower head at waist level so you can do your feet standing up, and a bench in the other side with a waterfall type shower where you can wash sitting down.


Ferdinand

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