December 22, 20205 yr Finally got the heat pump up and running. After clearing the air locks the system seems ok (?) but just need some reassurance that it is working. The house is obviously very cold (10 degrees) so it is going to take some time to warm up. How long does it take to see some improvement as it went up 1/2 degrees but I also turned on my mvhr today so a few things changed? What have people set the water temp for the ufh? House size is approx 26 x 9 internal floor area and is all ufh on a Passive slab so I know it is going to take a while. When I initially got it running the buffer tank heated up quickly but the blending valve was not adjusted so as soon as i altered that the heated water went into the ufh pipes and all the heat just dissipated so I guess I am after as much info regarding the first time of turning on the ufh and the running of there after, please!! I know you have to warm the slab up slowly but it could'nt get any slower but I am comparing it to rads as I have never experienced wet ufh before. TIA
December 22, 20205 yr Leave it on overnight and you should feel some warmth by the morning. Yes it is slow compared to radiators.
December 22, 20205 yr Author Just now, ProDave said: Leave it on overnight and you should feel some warmth by the morning. Yes it is slow compared to radiators. Thought so but it keeps defrosting so is that right as completely in the dark regarding this system?
December 22, 20205 yr Just now, Pete said: Thought so but it keeps defrosting so is that right as completely in the dark regarding this system? What flow temperature have you got coming out of the ASHP? I would not expect much defrosting unless you have that set really high. Set it down to about 35 degrees if it's presently higher.
December 22, 20205 yr Author 1 minute ago, ProDave said: What flow temperature have you got coming out of the ASHP? I would not expect much defrosting unless you have that set really high. Set it down to about 35 degrees if it's presently higher. we turned it up to 45 degrees to see if we could get some improvement on the floor temp so should we turn it back down again?
December 22, 20205 yr Have you got thermometers on the UFH manifold? You can see flow and return temps? If not can you at least feel it’s warmer on the flow side? Have you got your flow regs opened and at actuators open?
December 22, 20205 yr Author Just now, Gav_P said: Have you got thermometers on the UFH manifold? You can see flow and return temps? If not can you at least feel it’s warmer on the flow side? Have you got your flow regs opened and at actuators open? I have a gauge on the inlet manifold reading about 19 degrees and it is warmer than the return but I would have thought it would be warmer than this? I have just turned the water temp setting on the ashp to 20 degrees to see what that does as at 45 degrees was causing defrosting issues
December 22, 20205 yr 9 minutes ago, Pete said: I have a gauge on the inlet manifold reading about 19 degrees and it is warmer than the return but I would have thought it would be warmer than this? I have just turned the water temp setting on the ashp to 20 degrees to see what that does as at 45 degrees was causing defrosting issues Do you have flow around the UFH circuits? Meaning can you see the flow regs on the manifold moving up when it’s turned on? That amount of defrosting is concerning. Mine rarely defrosts and it’s working pretty hard as it’s too small for the demand. I’d run it at about 35 and then see. Have you checked the blending valve on the UFH manifold? Make sure that’s not turned right down.
December 22, 20205 yr Author 2 minutes ago, Gav_P said: Do you have flow around the UFH circuits? Meaning can you see the flow regs on the manifold moving up when it’s turned on? That amount of defrosting is concerning. Mine rarely defrosts and it’s working pretty hard as it’s too small for the demand. I’d run it at about 35 and then see. Have you checked the blending valve on the UFH manifold? Make sure that’s not turned right down. will do
December 22, 20205 yr Author 9 minutes ago, Gav_P said: Do you have flow around the UFH circuits? Meaning can you see the flow regs on the manifold moving up when it’s turned on? That amount of defrosting is concerning. Mine rarely defrosts and it’s working pretty hard as it’s too small for the demand. I’d run it at about 35 and then see. Have you checked the blending valve on the UFH manifold? Make sure that’s not turned right down. Blending valve is open and the flow pipe is barely warm so something is not right
December 22, 20205 yr 1 minute ago, Pete said: Blending valve is open and the flow pipe is barely warm so something is not right That maybe because you’ve turned it down to 20 degrees. It will take a while to up the temp and it’s kind of iterative. It heats the return up a small amount at a time. So could take hours to get the circuit up to 35 degrees if the UFH is is taking all the heat out of the system to get up to its operational temp. keep the thermostats calling for heat and leave it running over night. Assuming the UFH manifold is set up right, the house should be warm by morning.
December 22, 20205 yr I’ve just realised you have a buffer tank. What temp is that set at? Get that up to 35+ degrees, ideally 45. Make sure the DHW isn’t calling for heat as that will steal the heat quickly. crank the room stat up high and wait.
December 22, 20205 yr 11 minutes ago, Pete said: Blending valve is open and the flow pipe is barely warm so something is not right Not the case. Your body temp is fooling you so ignore it. If the UFH manifold loops feel warm or even ‘slightly hot’ it’s too hot. You need to set the ASHP as said to ~35oC and the UFH manifold blending valve to 22-24oC and bugger off out fir 48 hrs. Until then, nowt will change significantly. You’re ridding the house of a HUGE amount of ‘cold’ stored energy so patience is required and results will follow
December 22, 20205 yr Author 1 minute ago, Nickfromwales said: Not the case. Your body temp is fooling you so ignore it. If the UFH manifold loops feel warm or even ‘slightly hot’ it’s too hot. You need to set the ASHP as said to ~35oC and the UFH manifold blending valve to 22-24oC and bugger off out fir 48 hrs. Until then, nowt will change significantly. You’re ridding the house of a HUGE amount of ‘cold’ stored energy so patience is required and results will follow Nothing has changed internally temp wise for over 7 hours? The unit keeps defrosting as well, is this right?
December 22, 20205 yr Author 2 minutes ago, Gav_P said: Where in the country are you? What’s the weather like there? Its saying 5c outside
December 22, 20205 yr 4 minutes ago, Pete said: Its saying 5c outside So if there is plenty of moisture in the air I would expect it to defrost every 30-60 minutes if it’s working at full tilt (which I guess it is at the moment). But that should only be for a minute or so. ignore the defrosting and do as nick says.. leave it running and come back later.
December 22, 20205 yr Author 1 minute ago, Gav_P said: So if there is plenty of moisture in the air I would expect it to defrost every 30-60 minutes if it’s working at full tilt (which I guess it is at the moment). But that should only be for a minute or so. ignore the defrosting and do as nick says.. leave it running and come back later. It just feels weird to not have warm flow pipes that's all. Patience is not my forte!
December 22, 20205 yr @Pete turn the MVHR off ... It will not be helping and it will be cooling the house not warming it as you’re pulling in 5°C air that will be being warmed to 8°C or so by the air leaving at 10°C from the rooms. UFH flow needs to be up toward 28°C to get a slab to give you anything like a 17-18°C room temperature. I would set the flow temp on the ASHP to 35°C and run it for 48 hours constant and then see where it is at.
December 22, 20205 yr Author 6 minutes ago, PeterW said: @Pete turn the MVHR off ... It will not be helping and it will be cooling the house not warming it as you’re pulling in 5°C air that will be being warmed to 8°C or so by the air leaving at 10°C from the rooms. UFH flow needs to be up toward 28°C to get a slab to give you anything like a 17-18°C room temperature. I would set the flow temp on the ASHP to 35°C and run it for 48 hours constant and then see where it is at. Have done, will just wait and see. Thanks
December 22, 20205 yr Author 12 minutes ago, PeterW said: @Pete turn the MVHR off ... It will not be helping and it will be cooling the house not warming it as you’re pulling in 5°C air that will be being warmed to 8°C or so by the air leaving at 10°C from the rooms. UFH flow needs to be up toward 28°C to get a slab to give you anything like a 17-18°C room temperature. I would set the flow temp on the ASHP to 35°C and run it for 48 hours constant and then see where it is at. The other option is direct heating or use the inbuilt weather curve so not sure which setting to use to acheive the best results?
December 22, 20205 yr Just start with a couple of days of low heat and then start to ramp it up. Will take time but will be fine.
December 22, 20205 yr 1 hour ago, Pete said: Nothing has changed internally temp wise for over 7 hours? The unit keeps defrosting as well, is this right? 7 hours is a long blink. Chill out and leave it alone for the 48 hrs. Have you checked the isolation valves are all fully open on the pump isolation valves / other valves? May he strangled flow somewhere simple. Check pump ISO’s first.
December 23, 20205 yr Author 8 hours ago, dpmiller said: What is your design floor temp? Not a clue. Designed it three years ago on Loopcad so will have to start searching!!
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