boiler temp for UFH

22 Jul 2012
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United Kingdom
i was wondering what the most efficient/optimum temperature for my new glow worm ultracom 2 30cxi would be set at for working with my new underfloor heating system. i have no radiators to worry about.
is it lower the better or is there a best temp range to keep it in for the condensing to work.
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Assuming your new appliance was installed by a responsible RGI, what temp did he leave it at?

Also, dependant on the floor type and materials used (never mind if you want to scorch the soles of your feet) there will be a max temp above which you set it at your own risk...

Actually, the blending valves will mix it at a safe temp anyway, but a lower flow & return temp will assist in best efficiency of the combustion process.

So, let us know what temp the installer set it at, and/or what the UFH manufacturer suggests.

Who says he has blending valves?

With all UFH they are not required and the usual way to fit UFH in most of Europe!

well done Tony,

if the OP wanted optimize the control technology of the boiler he could install an out door sensor and a climapro room stat..
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he's been trying to find out too. he left it at 55 but says he will try & find out the most economical temp to set it to.
no sure what you mean by a blending valve unless you mean the thermostatic control valve that has a brass probe inserted just before the manifold.
Due the the excessivly long time constant of UFH a simple weather comp system is not going to work very well.

It would always be two hours behind.

In fact the only system which would have much chance is a complicated adaptive one.

also i forgot to say each room has a programable stat. not that that got a lot to do with what i am asking.
OK Tony & Alec I stand corrected :oops: , I don't fit a whole lot of UFH, and neglected the 'no rads' bit as I warmed to the task...

Do they operate a solenoid valve on each room's UHF loop?

Of course by the time the room stat has responded the room is going to seriously over shoot the required temperature. But turning them down a bit will help on the heat up. But that will then be too low for when it needs to be on again.

Tony thats most cases the time lag of the building matches the time lag of the floor, so actually weather compensation is ideal for UFH..

clearly though the system needs to ve se t up correctly

Tony you are welcome to come and see some of my installs in London UFH only, all with compensation controls..but no zonal controllers and in some case no room sensing (ie outdoor sensing only - note you can only do this with a few boilers..)
Each zone is controlled by a programmable stat controlling an actuator on the manifold. I'm not too concerned about the room temps I can fine tune them later. It's the temp on the boiler that's needed. Does the boiler run most efficient at what temp.
The lower the temperature the more efficient the boiler...some mixing valves need high temperatures..

what has been installed is standard practice in the UK, but is not optimal..
Thanks alec .
Can I just ask is this your personal choice or one from the manufacturer's. So if I lower it to 40 deg it will work & condense better than at 50 deg.
Thanks again.
the valves and the system will be desigend around certain paramarers..bu the system will work at lower boiler temperatures..

so if it performs well when low thats fine, if not just raise it!,,
Try it at 40C for a start. If that is not enough in the coldest winter weather, raise the temp a bit. The underfloor people may have stated a maximum temp; it doesn't have to be that high at all times.

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