Under Floor Heating Balancing

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andyl3004

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Hi

Have installed an Emetti UFH system under Agilia A screed. Two zones, 3 loops (one large kitchen for 2 loops and one utility for one loop) in a refurbishment/extension.

Loops 1&2 kitchen, Loop 3 utility.

It has been running for ten days now, I started at 20 C and raised to 55 C by 5 per day. Loops 1 and 3 are able to be fully opened to just under 4L/m but loop 2 cannot be opened to more than just under 3L/m. I think this is because the system has not been balanced correctly? Can anyone help? I altered the called for flow rate to just below 3L/M as that was the most loop 2 could call for so I asked each loop to call for the same.

The flow meter on loop two showed the water level in the window at about a third less than that of loops 1 & 3. In fact, at the start of the commissioning cycle, loop 2 window looked almost empty of water but it went up as I increased the temperature over the week - I assume because of pressure, however, the pressure on the whole UFH system has dropped from about 1.6b to about 1.4b? Also, it is hard to tell, but either all the flow meter windows now are completely full of water, or they are empty - there is no air gap a the top of the window at all.

I have just started to lower half of the commissioning cycle now. I have continually check the flow pipes at the manifold and the different areas of zone 1 to see if the lower flow rate on loop 2 feels like it is making a difference, but it is hard to tell.

Does anyone have any suggestions about how to balance the system correctly? The actuator heads are not connected yet, the system is running via mains power (3a fuse) so it is permanently on.

Also the temperature guage shows about a 5 degree reduction every ten minutes, then the boiler kicks in and the system reheats to the required temperature - is that right that it should lose heat so quickly?

Any advice welcome - can post pictures if needed.
 
Who designed the system? Flow rates are partly dependent on loop length and system designers will usually quote design flow rates for each loop

Did you pressure test the system before and during screeding? What pressure was used?
 
Thanks Dan and Muggles for quick response

I was not given a design or specified a flow rate by the company who installed it. They did pressure test before and during but I do not know what pressure this was at.
 
Why are the installers not commissioning it? Can you call them and ask what the design flow rates are? The flow rate of each loop is dependent on the other loops, so it's vital information in order to achieve correct balance.

If also be asking for details of pressure testing - if the pressure is dropping, you have a leak somewhere and you need to know when the leak started (unless air is still present in the system, in which case that might be getting out, but if it was filled up correctly using the commissioning valves there shouldn't be any air)
 
Flush loops with mains water to expel any air. I'll bet that's where your problem lies.
 
Thanks Rouguetrader but the Wilo control unit on the manifold (not the wiring unit or the mixing valve/pump stat - see Emmeti U9700090 T3 Control Group) has one dial which has a venting option which I have already down at the start of the commissioning process - that automatically defaults to max. set differential pressure after ten minutes of venting so there should be no air in the unit. Also, I have opened the manual vent at the top of the flow bar at the start of the commissioning cycle and that just let water straight out. and when the cycle was heating up, extra space above the water in the flow window of loop two began to show spots of condensation and then these were swallowed up as the flow level rose with the increase in temperature.

Don't know what you think of that? Muggles, I will contact the installers, though they are primarily a screed/UFH installers and don't tend to commissioning the systems - they said that was the plumbers job. But with the actuators still needing wiring up (like the whole wiring centre) I just wanted to get the commissioning cycle started. This is a self-build project
 
You'll need to flush those loops with mains pressure, a venting setting on a circulator won't shift a loop full of air.
 
roguetrader said:
You'll need to flush those loops with mains pressure, a venting setting on a circulator won't shift a loop full of air.
Click to expand...


What he said

You need to disconnect and cap off the pump and mixing valve set, and fill each loop individually using the commissioning cocks on the other end of the manifold
 
I have to say that I am wondering what the flow and return temperatures are in each loop.

Are all the loops the same length?

Tony
 
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