UFH test pressure and duration.

[MikeSharp01]

Seems to be a lot out there on this but thought I thought I would ask here and see if I can approach a definitive answer. 5 bar / 6 bar and for how long. I will test our UFH pipe work tomorrow and so need a test pressure and duration. Don't say 5 bar for ever! Our pipework says it's good for 10 bar but I doubt a circulating pump will manage much more that a couple of bar worst case. I guess the test is to look for leaks and stretch / expand l the pipe. 

[Onoff]

My one loop for the bathroom UFH held 3bar for months...in fact years!

[DeeJunFan]

I tested mine at 3 bar for about 3/4 weeks before screed pour.   1 manifold lost pressure as there was a very small drip from the pressure gauge connection, noticed that after about 2 days. 

 

Once that was tightened and refilled all was steady. 

 

When the screed was poured the pressure went up to about 4.5 bar and held there steady for another few weeks without issue. 

 

[nod]

We are commissioning ours on Friday

Its had 4 bar of air pressure for the last eleven months

[MikeSharp01]

All sounds great but a couple of things I am still not clear about. Presumably I do not need to keep rhe pipes under pressure during the pour they are only 70mm down on the slab. Secondly I will be pressurising each loop separately as we cannot leave the tails sticking out during the pour. I can leave the water in but not pressurused.  

[nod]

11 minutes ago, MikeSharp01 said:

All sounds great but a couple of things I am still not clear about. Presumably I do not need to keep rhe pipes under pressure during the pour they are only 70mm down on the slab. Secondly I will be pressurising each loop separately as we cannot leave the tails sticking out during the pour. I can leave the water in but not pressurused.  

I opted for air as I thought there could be a chance of the pipes freezing during the winter months

 

[epsilonGreedy]

2 hours ago, MikeSharp01 said:

All sounds great but a couple of things I am still not clear about. Presumably I do not need to keep the pipes under pressure during the pour they are only 70mm down on the slab.

 

 

I understand the opposite, some pressure during the pour is recommended.

 

If the formal pressure test is X, then the pressure to be maintained during pour is half X.

[PeterW]

47 minutes ago, epsilonGreedy said:

 

I understand the opposite, some pressure during the pour is recommended.

 

If the formal pressure test is X, then the pressure to be maintained during pour is half X.

 

Pressure will rise during a pour as the concrete curing heats the water and the pressure rises. You pressurise to ensure that the pipe hasn't been damaged during the pour although in a small number of cases - usually using liquid screeds - there is no need.

 

3 hours ago, MikeSharp01 said:

All sounds great but a couple of things I am still not clear about. Presumably I do not need to keep rhe pipes under pressure during the pour they are only 70mm down on the slab. Secondly I will be pressurising each loop separately as we cannot leave the tails sticking out during the pour. I can leave the water in but not pressurused.  

 

You can link all the tails together using standard Tees or elbows to make a full loop - what pipe are you using..?? You may need 16x15mm adapters but you can re-use these later in the build to use up the spare UFH pipe as supply pipes.

[TerryE]

Mike, we didn't even bother pressure testing ours until we commissioned the system , but that's because we used an MBC in-slab UFH so the slab team laid the UFH pipework straight from the drum and the concrete went down a day later.  I filled the system and left it for a day to get into thermal equilibrium and cranked it up to 6 bar for a couple of hours,  with just the manifolds and no expansion, just to double check for leaks, so even a few cm³ of loss would have collapsed the pressure. 

 

We have manual top-up from the rising main after the DCV through a double valve system to the expansion vessel if and when needed, and set it up to run at 1 bar.  9 months later and it's still at 1 bar.  Though as Peter says some +/- around this because of the varying expansion of water in the system as the temperature varies.   

 

IMO, you only need to run the UFH at whatever pressure needed to prevent cavitation for your flow rates.  I can't see any advantage in running at a high pressure than needed.

Edited July 31, 2018 by TerryE

[DeeJunFan]

4 minutes ago, TerryE said:

Mike, we didn't even bother pressure testing ours until we commissioned the system , but that's because we used an MBC in-slab UFH so the slab team laid the UFH pipework straight from the drum and the concrete went down a day later.  I filled the system and left it for a day to get into thermal equilibrium and cranked it up to 6 bar for a couple of hours,  with just the manifolds and no expansion, just to double check for leaks, so even a few cm³ of loss would have collapsed the pressure. 

 

We have manual top-up from the rising main after the DCV through a double valve system to the expansion vessel if and when needed, and set it up to run at 1 bar.  9 months later and it's still at 1 bar.  Though as Peter says some +/- around this because of the varying expansion of water in the system as the temperature varies.   

 

IMO, you only need to run the UFH at whatever pressure needed to prevent cavitation for your flow rates.  I can't see any advantage in running at a high pressure than needed.

 

Since our system has been commissioned its now running at about 1.5-1.75 Bar I was thinking it was supposed to be higher but the plumber said it was fine. 

[TerryE]

1 minute ago, DeeJunFan said:

Since our system has been commissioned its now running at about 1.5-1.75 Bar

 

You need to look at the pressure drop curves for your pump at your flow rates and have a sensible margin.  Too low and the pump starts to sound noisy.  I might have had a memory mindfart: ours might be at 1½ bar, I will have look the next time I am sitting on the can in the downstairs loo. 

 

 

[Temp]

Our UFH system is vented so runs at 0.1 to 0.3 bar. Not had any issues with noisy circulation pumps. They are Grunfos pumps.

 

Just make sure they are mounted in the correct orientation, you can't just put them in any old which way.

 

[MikeSharp01]

Thanks all. @PeterW I can make a continuous loop so I may do that and then pressurise it a bit. Thanks @TerryE we have the UFH pipes tied to the lower mesh and pressure testing yesterday @ 7 bar went OK once we found that the pressure tester had a slight leak, one, one more loop to test today - concrete pour is tomorrow so no great exposure for the pipes. 

[Nickfromwales]

You really would have to be careless or malicious to damage pert-al-pex / pex-al-pex pipework tbh. My screeders wheel full barrows of screed over them and tramp back and forth without even a bump. Ive caught the odd numpty up-ending the wheelbarrow onto the pipe, but it just seems to compress the insulation. 

Flow rates are typically between 2 and 5 lpm as dictated by the weir flow gauges on the manifold. Pressure can be near zilch, or up over 2 bar and I cant honestly say ive ever heard an ufh pump tbh they're almost silent. If the manifold is between 5 and 9 ports you'll be on pump setting 2.

Id recommend the Ivar Dualmix pump and blending set, coupled with a Wunda manifold. The Wunda manifold is telescopic so you can adjust the centres to match whichever 3rd party manifold arrangement you bought. 

 

[PeterW]

27 minutes ago, Nickfromwales said:

recommend the Ivar Dualmix pump and blending set, coupled with a Wunda manifold.

 

Whats the benefit of this @Nickfromwales as the Ivar is more expensive and the only difference seems to be for a capillary thermostat which is useful on the low temp flows. I think the auto balancing heads are the way forward on a lot of this tbh... 

[Nickfromwales]

The generic thermostat blending valves fall over when you ask them to run at low temp. They choke the flow when the return temp raises enough to leave no differential temp between flow and return. You cant blend hot with cold if your cold is the same temp as your flow which is exactly what happens when your up to temp. All gravy whilst your cold and getting UP to temp, but when your there the TBV just goes into meltdown. Many who think it doesn't should sit and listen whilst its running and you can hear them whining and attempting to strangle the flow. If you have an adverse installation which requires a primary circulation pump, then be 100% sure to fit a full 22mm gated bypass to allow flow back to the heat source when the TBV has had its fill. 

This is as always case specific advice and most are PH / similar, so you really need linear heat influx and the Ivar with the capillary blend set does work like a dream. Absolutely whisper silent. I suspect there are cheaper ones, but the Ivar comes with a top-notch Grundfos pump which is super energy efficient ( >A+ iirc ). £300 with the Vodka and Tonic but money well spent imo, and also has in-built adjustable bypass in the control group so one less bit of kit to buy and install..  

[Alexphd1]

Good timing with mixer valve advice, been eyeing up a £60 esbe valve for low temps ufh and adding own pump. Although prob go with mixer mentioned above what's the chance of getting away with using a standard efficiency grundfos pump ( I still have a "few" lying around) ?

Edited August 1, 2018 by Alexphd1

[Alexphd1]

Deleted I am wrong again ?

Edited August 1, 2018 by Alexphd1

[le-cerveau]

I used ESBE valves in my setup.  VRG 130 rotary valve with a CRA 110 thermostatic controller for the mixing valve.  MY setup is custom with one mixing valve supplying the two pumped manifolds.  This draws heat from the SunAmp (PCM34) and blends with the return, temp set at 26C and fully adjustable.

 

I also have VRG 230 diverting valves used to select the no-heating required/cooling setup.

 

Not cheap, but totally configurable, though my plumber didn't have a scooby on how to install them and had the inserts 180 degrees out so initially it wasn't functioning as expected.  I resolved this by simply removing the controllers, rotating the drive shafts to the correct positions and re-assembling, just a question of reading the instructions!

[Pete]

 

38 minutes ago, le-cerveau said:

I used ESBE valves in my setup.  VRG 130 rotary valve with a CRA 110 thermostatic controller for the mixing valve.  MY setup is custom with one mixing valve supplying the two pumped manifolds.  This draws heat from the SunAmp (PCM34) and blends with the return, temp set at 26C and fully adjustable.

 

I also have VRG 230 diverting valves used to select the no-heating required/cooling setup.

 

Not cheap, but totally configurable, though my plumber didn't have a scooby on how to install them and had the inserts 180 degrees out so initially it wasn't functioning as expected.  I resolved this by simply removing the controllers, rotating the drive shafts to the correct positions and re-assembling, just a question of reading the instructions!

Not many blokes read instructions!

[dpmiller]

https://www.heatingcontrolsonline.co.uk/ivar-thermostatic-mixing-valve-pump-set-p-1073.html?search=ivar

 

dualmix on it's own here if anyone needs it.

[epsilonGreedy]

On 31/07/2018 at 10:01, PeterW said:

Pressure will rise during a pour as the concrete curing heats the water and the pressure rises. You pressurise to ensure that the pipe hasn't been damaged during the pour although in a small number of cases - usually using liquid screeds - there is no need.

 

 

I spoke to the pro installer of a flowscreed job near me this week and he confirmed my advice posted in this thread i.e. some pressure should be maintained during the pour. He said the objective is that when the UFH returns to normal operating pressure post pour & cure the UFH pipes can contract and expand a little during heating cycles without creating cyclical pressure on the slab. Some pressure in the pipes during the pour would also reduce risk of the screed compressing the pipes though he added this is a low risk with a 50mm flow screed pour.

 

The guy also advised me to think ahead while laying the footing blockwork and allow for a circuit that does not result in a Clapham Junction of UFH pipes running through a door threshold.

[Alexphd1]

@Nickfromwales

Can you confirm which ivar pump has the low temp setting. I bought the above one and it's mim is 35 degree.

 

 

[Nickfromwales]

33 minutes ago, Alexphd1 said:

@Nickfromwales

Can you confirm which ivar pump has the low temp setting. I bought the above one and it's mim is 35 degree.

 

You want this one ?

[joe90]

With our UFH running temp on an immersion within the buffer tank (till I get my ASHP working!) with the TRV on the manifold set to frost I still get 24’ into the manifold and after 24 hours the house s too hot. I bought the Salus auto balancing control as advised by @JSHarris. I hope this controls the temp more accurately. Also I bought the Wilo pump as it’s also whisper quiet .