blend valve query


All,
(first post here so pls excuse any poor form etc ...)
I have recently taken over a children's nursery and need to do something to regulate the temperature of the scaldingly hot water that issues from the boiler fitted by the previous owner.
A plumber who recently did my Corgi cert said the boiler was very cheap and nasty (Worcerster 24i RSF) but was actually installed properly and was functioning correctly. He recommended fitting a thermostatic blend valve in the system. Having looked at these online tonight it is clear that this is exactly what I need. I am sufficicently sensible and capable with copper to fit one myself, but I have a few questions before I make a right pig's ear of it ...
High vs low pressure? The nursery has a sealed water system - does this automatically make it high pressure?
How close to the taps should the valves be fitted? As close as possible I imagine?
I was planning to install them inline in the hot water pipes with a tee across from the cold water to feed the blend water - is this the correct (and simplest) way to do it?
Where is the best source for these valves - my local Travis Perkins Plumbing Centre only keeps one flavour of valve and it doesn't look like an inline type to me ...?
TMV2 , TMV3 - what's that all about then?
Any other pitfalls or top-tips I should be aware of?
Many thanks in advance
Yours hopefully
Steve
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I usually put one big one to controll whole house. Do you have different temp demand? ie:laundry. If you have ony one temp need turn it down at boiler if possible.(Im not familiar with your brit boilers) do you have hot water recirc? This will change pipeing. the directions should cover that.

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I want to keep the taps (faucets ...) used by the children at a very safe temp (sub 40°C), while the washing up water should probably be higher for hygiene reasons ...
The boiler is very cheap and nasty and has a single temp control for the central heating and hot water. Even on the lowest setting there still seems to be a slug of VERY HOT water that hits the taps about 10 secs after turning on ... OUCH!
no hot water recirc so should be a fairly simple installation.
We have fairly strict guidelines here on placement of blend valves - they must be within 2m of the outlet etc ...
I'm looking at various suppliers and designs at the moment and should be attempting it next weekend.
Are vented or closed systems the norm over there for domestic dwellings?
thanks for your time
Steve
Ned Flanders wrote:

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"normal" for us is closed system. we pressurize the system with a bladder tank typically.
The only open systems I see around here on a regular basis are solid fuel boilers with super heated water in them.
I am not sure what brand you will have over there but any of the under sink versions here are OK.
http://www.watts.com/scripts/pro-products.watts?_cfg=./db/pro-products.cfg&_fil Êt2%3d'Point_of_Use'.and.cat1%3d'Tempering_Valves'.and.div%3d'_watersafety-flowcontrol'&_sn=pro-products&_tar=_view5_watersafety-flowcontrol

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"""I am not sure what brand you will have over there but any of the under sink versions here are OK.
http://www.watts.com/scripts/pro-products.watts?_cfg=./db/pro-products.cfg&_fil Êt2%3d'Point_of_Use'.and.cat1%3d'Tempering_Valves'.and.div%3d'_watersafety-flowcontrol'&_sn=pro-products&_tar=_view5_watersafety-flowcontrol"""
Check your local code it might need to be one like the one at the top of the page.

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thanks
I've found sonething very similar over here - I'm just waiting for a price!
Here's our "specials" regs (TMV 3 etc ...) http://www.buildcert.com/TMV/Default.asp . I'll check with my friendly local Building Regs officer if he has a preference for TMV 2 or 3 in this application - this is essentially a domestic installation, but perhaps TMV 3 gives better thermal control more suitable for high risk users? wtf do I know ...
best regards and have a good day y'all
Steve
Ned Flanders wrote:

http://www.watts.com/scripts/pro-products.watts?_cfg=./db/pro-products.cfg&_fil Êt2%3d'Point_of_Use'.and.cat1%3d'Tempering_Valves'.and.div%3d'_watersafety-flowcontrol'&_sn=pro-products&_tar=_view5_watersafety-flowcontrol"""
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SUPER HEAT ?!?
There is that baaaad word again.

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lol i was wondering if you heard that. : P

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This sort of thing looks good.
http://www.rwc.co.uk/Public/tmv/HEATLS2.pdf
I assume the layout is:
hot in __________ warm out | | cold in
drd wrote:

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yes, just make sure you don't need the tamper resistant type. There might be a local code which calls for that.

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all done
the valve was a very reasonable £40 ($70) for a tamperproof TMV3 spec (suitable for hospitals, schools etc) and the install went very smoothly given the close run of the pipes and limited space etc.
I checked the water temp after and it is now very well controlled to a comfortable (and safe!) 40°C rather than the 60°C is was before (and still is from the other outlets!).
I'll be installing a few more over the next few days ...
all the best to all you proper plumbers out there and thanks for your time
Steve

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good work and you are welcome.

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