Been looking at blending valves for a floor heating circuit. Seems they are mostly sold as TMV3 for protecting basin outlets etc. Does anyone know if the TMV3 spec allows it to be set as high as 55deg?
TOby.
Have you thought about a roomstat to control a motorised valve ? The valve can be configured as two or three port and the stat' can be wired to allow both opening parameters.
BES have the Danfoss valves and heads and I think another version. Do a search on Danfoss. UFH blending valves are faster acting.
wired to allow both opening parameters.
Going to have a digistat to switch the zone valve and fire the boiler for room temp control, still need water temp control as well. Yep. Thought about a 'binary' control with a motorised valve, shoot a load more hot in then stir that around for a while. I'm more keen on the proportional blending you'd get with a self-acting valve though. It's just I can get my hands on a TMV3 mixer for £32, whereas BES would do the 3 port UFH valve for £68+21+63(*).
Can I get hot enough water out of a TMV3? I've hunted high and low for the specs but drawn a blank.
Toby.
(*)
Found this: 22mm UFH mixing valve PB219058 £92.80+v As it's only going to be a 15m circuit I'm seeing if I can economise with a £32 TMV3. Am I cutting too big a corner?
Toby.
Price up the Reliance UHF blenders I gave the URL for. If the TMV3 is easily accessible, I suppose you could see how it works. If it is too slow to respond then change for a proper UFH blender.
Where did you find TMV3s for £32?
Typically a UFH system does not go above 50C. It can be designed to operate at much lower temps than that.
"IMM" wrote
Local independant (York) merchant has them. No boxes just polybagged. No idea what brand. £32 + v of course, 22mm is £38 + v Slightly unusual shape, not the standard T, they call them 'inline' TMV
H>>>>XXX The XX part is a vertical cylinder XXX>>>>Flow C>>>>XXX XXX \|/ Valve
Toby.
Technical Specification: Temperature adjustment range : 30 - 50 °C. Temperature control : +/- 2 °C. Max. hot inlet temp.: 85 °C. Operating pressure range : Low 0.2 - 1 bar, high 1 - 5 bar. Max. working pressure : 10 bar (static). Min. working pressure : 0.2 bar (dynamic).
Part No.DescriptionUnit PriceQty
12162 15 mm £50.99 12163 22 mm £52.53They look like the Screwfix ones (which are cheaper for the 15mm) but I haven't bought the BES one so can't be sure.
cheers
-- John Stumbles
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Electric valves are not required - a thermostatic mechaniocal by pass is entirely adequate.
Oh heck - a tiddler?
So not even a separate UF pump?
You know i'd frankly say 'sod it' and lay the plastic pipe in some insulation if its being screeded, and forget about it (insulation) if its under a suspended wood floor.
The point of temp reduction is to protect the floor, not the pipe after all.
Any method that stops you cracking teh cioncrete by limiting heatflow will do.
e
He wanted electric. Duhhh!!!
I'm just wondering how many types of underfloor heating there are on the market now'a'days. It seems to be increasingly popular with the people joining in this group, so someone should start compiling a site dedicated to it. Or have I missed any sites that are now doing this ?
I've seen my systems (all eight of them now :-)) running up to a pipe temperature of 65 degrees on the flow side with no adverse effects to any parts of the structure or flooring, and I think you'll agree that 65 degrees is enough to keep the whole of the house loverly and cosy in the winter months.
I do have to admit that two of the systems have pipework buried in screed floors and these did show some signs of causing cracks around where the pipes are buried, but the cracks were filled with a very thin layer of a more wet mix and never reappeared. I put it down to me firing the system up to soon after laying the mix and it hadn't had time to cure properly.
None of the systems I've installed have anything other than normal central heating equipment installed in them, i.e. boiler, circulating pump, motorised valves and roomstats, and the people who I've installed them for, over many years now, have always complimented the way in which they work and the way their friends talk about how their systems always seem to have some kind of fault or another.
I've always just treated the pipework under the floors like any other kind of radiator, which it is, and never done anything fancy to systems other than put my installers mark on them. All in all, I think that to much is being engineered into these systems and that is what is causing a lot of problems and whoo haa about how hot it has to be and how far down the pipes must go. If anyone has felt the heat that radiates from the back of a standard radiator and goes against a stud partition wall, then it is exactly the same for the pipework under a floor.
I don't see the need to over engineer anything and I think it only causes more grief than it's worth.
I thank you, and good night. :-))
There is a difference to over-engineering and not doing it correctly. You should learn about UFH and how to design and install it properly. UFH runs at low temperatures for a variety of reasons, preventing cracks in the screed being only one.
UFH is notorious for being either too hot or too cold when the weather changes, as it does in the highly changeable UK climate. This is because of the sluggishness of the system, the very slow response rate. Proper blending controlled by inside temperatures and feed forward control by outside weather compensation predicts the eventual temperature fall or rise reducing the too hot or cold discomfort.
I hope you are using proper barrier pipe under the floors, PEX. Are you? NEVER run UFH over 50C.
It is bad enough attempting to get know-it-all amateurs to comprehend matters, and you do this for a living?
UFH amounts to only a few %age points of the overall systems installed in the UK. People only install it to eliminate rads. No other reason.
No I don't. I want a mechaniocal blender.
Toby.
Why Thank You. :-)) I wouldn't call them "CRUDE" systems as such, but I would call them "BASIC" heating systems. I don't see the point of engineering in, what is not absolutely necessary to make the system work at quite a high efficiency already. If you think about the pipework in place between the joists, working out to two lengths of pipes in each gap, then consider that they actually only radiate their heat into the space between the joists. This heat is then permeating evenly through the floor and into the living space above.
With this simple principle at work, and even with floor coverings such as carpet or laminates, the heat radiating through to the living space is kept at rather a comfortable level. With the addition of just one roomstat', positioned as close to the centre of the property as possible and at about light switch height, the temperature at the seating level is kept at a set rate.
What has been seen on these systems, is the fact that the running costs seem to be much less than friends tell of their systems. I think this is mainly due to the boiler only heating the water to the desired temperature with its own internal 'stat, and the fact that, when the system has been running for an hour or so, the area around the pipework has less heat loss due to it being already raised to a higher temperature. This then causes the boiler to fire up a lot less times in the initial start to compensate for the dramatic heat loses which occur, for a lot longer period, to a normal radiator in open air.
All I know is that I have been recommended to install two more of the same systems this year, and have arranged it so that the people move out to a holiday home for a few weeks this winter. I ask them to do this for only one reason, that is because it is a big upheaval to live in the same house with all the floor boards lifted to install the pipework. This is the only drawback with a system like this. But the holiday home is my own, and it is all in with the price of the system.
I allow two weeks for each installation, just to be on the safe side, to give plenty of time for testing and balancing of the systems. And this also allows for any settling times, finishing of decor' and things, between jobs that the install needs. This is all done before the people arrive back and means they don't have to walk in to real mess and dusty atmosphere.
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