Balancing UFH

chriselevate · 22 Dec 2018

I’m familiar with the concept and ways to balance a radiator system so I’m trying to apply the same logic to my UFH system.

One quick questions... should I balance the return 22mm valve that is attached to the bottom of the manifold? Leaving it wide open seems silly as the pressure is just whizzing into the mixer and straight out of the return. I guess in this situation you can think of the whole UFH manifold as one big radiator so it needs balancing in the same way? Or should I just leave the return value fully open?

Also, should the automatic actuator heads have the sensors just clipped to the flow and returns (like in the photo) or should they be ideal slid upwards to “touch” the metal fitting to measure the temperate difference better?

Photo attached.

Thanks for any help/advice you can give.

Madrab · 22 Dec 2018

You really need to get that PTFE tap off of those threads, it just aint right, the pump should also have rubber washers too to create the seal and shouldn't need tape either.
The UFH heating isn't balanced as in radiators, it's output is controlled by flow rate and temp & the return temp to obtain the desired m2 KW output from the floorspace and the overall temp within the space that it heats.

MeldrewsMate · 22 Dec 2018

chriselevate said:
One quick questions... should I balance the return 22mm valve that is attached to the bottom of the manifold? Leaving it wide open seems silly as the pressure is just whizzing into the mixer and straight out of the return. I guess in this situation you can think of the whole UFH manifold as one big radiator so it needs balancing in the same way? Or should I just leave the return value fully open?

One quick answers...Leave it fully open. It is a ball valve, designed to isolate. You are mistaken in thinking that the flow will 'whizz out to the return'. The mixing valve controls the flow INTO the UFH consistent with maintaining the UFH flow set temperature (at about 40C in your case). As the UFH is a sealed pipe system the rate water will return is the same as that entering. As thge UFH flow temperature reaches that set by this mixing valve the flow of water IN will be restricted, so the RETURN flow will also reduce accordingly.

chriselevate said:
Also, should the automatic actuator heads have the sensors just clipped to the flow and returns (like in the photo) or should they be ideal slid upwards to “touch” the metal fitting to measure the temperate difference better?

I've not seen these sensors before. It looks like you have temperature sensors on both flow and return for each UFH zone; I assume therefore, that the control system will modulate the associated valve to maintain the differential temperature in that loop.
I suggest you leave these sensors where they are, whatever error introduced in reading through a plastic pipe is consistent to both flow and return.

MeldrewsMate · 22 Dec 2018

Madrab said:
You really need to get that PTFE tap off of those threads, it just aint right, the pump should also have rubber washers too to create the seal and shouldn't need tape either.

I can't agree more. One (of many) of my pet hates is PTFE (tape) on threads that are not designed to seal, or on olives.

chriselevate · 23 Dec 2018

MeldrewsMate said:
I can't agree more. One (of many) of my pet hates is PTFE (tape) on threads that are not designed to seal, or on olives.

Thanks guys, yes I agree the PTFE take shouldn’t be there but it’s on because I couldn’t make it seal back can get fibre washers (30mm with 20mm centres) in order to redo it. It’s also very cold so don’t want to drain everything down no that it’s finally up and running.

On that note... I’m dissappointed that my rooms are still cold now it’s working. For example.... my lounge is trying to achieve an air temperature of 22 degrees centergrade but it will only get to 20 degrees despite being on all day. The flow temperature is 41 and return is 31 (as shown in the photo). If I increase the water temperature my floor probe (measuring the back of my 14mm engineered oak) kicks in at 27 degrees to prevent it getting any higher.

Any tips or suggestions please? I’m hoping it’s a setup issue as I’m really dissapointed (and cold) so far.

Thanks

Madrab · 24 Dec 2018

OK, this is where is comes to setting up the UFH properly.

You need to ensure the flow temperature is high enough and that the flow rate settings through the UFH are at the required rate to achieve the W/m2 output needed. It also comes down to the length of pipe runs there are and what floor covering you have as to how much heat it needs and how much it can transfer into the air over a given time.

It will take some time for any diy'er to get a system like that setup correctly and ultimately where experience with advanced heating systems come into its own.

kev25v6 · 24 Dec 2018

Mine took over a week of tweeking the flows to each of the zones to get the right temp in each room. Mine is set in concrete though and takes a day to see any difference. The boiler is set to 70 but the ufh regulates down to about 45 and that keeps the house at 23. I needed to move flow from the shortest runs to the longest runs to keep the temp the same through the house. It might be a bit different with a wooden floor though.

ironsidebod · 24 Dec 2018

The latest auto balancing setups work to a 7 degree drop across each loop. It's best to let the boiler get the water up to temp and steady and then set each loop when it is freezing outside. Different external temperatures will require a different flow rate to achieve a drop of 7 degrees hence balancing cannot be done in warmer months. I've learned a lot in a short time trying to get ours working nicely but will move to an auto balance solution in the near future.

A digital thermometer with two clamps you can attach to the pipes at the manifold comes in handy. They aren't expensive on ebay.

chriselevate · 25 Dec 2018

That all makes sense and yes, like you guys I’m getting the hang of it now it’s been in for a few days. I’m getting pretty good flows now there’s just something I need to clarify.

I can’t mix my temperature any higher than 40c as my wood flooring floor probe kicks in and stops calling for heat. I know they say 27c is the max temperature but I wondered if it was possible to set the probe auto cut off any higher than 27c as I can only get the room to 19/20c and I’d like to aim for 22/23c air temperature if I’m honest.

Or is there another way I can adjust things to try to achieve the desired temperature in the wood floor rooms?

Thanks

Madrab · 25 Dec 2018

Where does your floor probe connect into, is it a UFH thermostat?

chriselevate · 25 Dec 2018

Yes, 4 wall mounted neostat thermostats each with a floor probe. Two for the engineered wood floor and two for rooms where LVT is being fitted but not fitted yet.

The probes are 1m away from the wall, half way between two heating loops and in direct contact with the back surface of the wood.

ironsidebod · 25 Dec 2018

If you have a max floor temp of 27deg, then to get to a higher temp logically the heating needs to be on longer. I know you've run it all day and it can't hit the temp you want which suggests either the pipe spacings are too far apart for the heat loss of the room or you have a heat loss greater than the floor can make up. You need to look for draughty windows and the like these steal heat from UFH systems in a much more noticeable way then with radiators.

chriselevate · 25 Dec 2018

Yeah my logic was the same. The system is a wundafloor eps 400 system fitted in the way that they specified and designed.

I’d love to turn the water temperature up slightly and adjust the probe to allow a few degrees higher but obviously I don’t want to damage the wood.

The room is well insulated to be honest.

Any other thoughts on what I could do?

snb · 26 Dec 2018

Make sure you run the underfloor 24/7. Any timed off periods will affect the performance.

chriselevate · 26 Dec 2018

snb said:
Make sure you run the underfloor 24/7. Any timed off periods will affect the performance.

Yes, I guess it’s about re educating yourself on heating as it’s s very different system to radiators.

What do you guys think to the advice in here... https://www.ukplumbersforums.co.uk/threads/ufh-engineered-oak-flooring.95737/

It’s kind of suggesting that 27c floor probe cut off is that figure given by engineered wood manufactures to cover themselves in terms of warranty etc.

I’m just finding that the rooms with engineered wood just can’t get to a comfortable temperature at the moment with 40c on the flow and 30c on the return even when left running all day and night.

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