Nickfromwales Posted November 13, 2020 Share Posted November 13, 2020 Just now, Gav_P said: How do you size a buffer tank? When does it become oversized? Work out how much surplus you need to routinely dump and do the maths there. Pointless trying to dump a load of excess into a tiny ( 25L ) buffer. In honesty it’s rubbish as in the winter you’ll be lucky to see 25% PV output which will prob be enough to still be pulling from the grid most days ( so no surplus ). PV > heating = ? 2 Link to comment Share on other sites More sharing options...
oranjeboom Posted November 13, 2020 Author Share Posted November 13, 2020 Hope you got (your?) disasters sorted out @Nickfromwales!! Should have stayed at home seeing it's the 13th today! The very reason I won't do any plumbing today whilst I wait for the vinegar to do it's stuff on the willis heaters. I just bought the more expensive Wilo ("Green button technology") - overkill? I could get the other cheaper one if there's nothing in it to recoup a couple of beers. https://www.screwfix.com/p/wilo-yonos-pico-25-1-6-130-glandless-circulating-pump-230v/6153x 6m Max. Delivery Head vs 5m on the cheaper one. Not sure the flow max is correct on the more expensive unit: Thank-you! Link to comment Share on other sites More sharing options...
PeterW Posted November 13, 2020 Share Posted November 13, 2020 For anyone looking for cheap Wilo pumps for this sort of stuff, Toolstation have got the 5/130 at change of £90 https://www.toolstation.com/wilo-yonos-pico-circulating-pump/p75983 Link to comment Share on other sites More sharing options...
PeterW Posted November 13, 2020 Share Posted November 13, 2020 9 hours ago, oranjeboom said: I've taken one heater out and yes, some scale on that. I'll try and insert a camera in there to have a good inspection and then get some vinegar in there to soak for a while. Have you not got any inhibitor in the system ..?? If you are hacking into the system then worth adding one of the mag filters (cheap one here) which you can also use for dosing inhibitor into the loops. Shouldn’t be getting scale on a Willis as it’s a closed loop system. Link to comment Share on other sites More sharing options...
Gav_P Posted November 13, 2020 Share Posted November 13, 2020 1 hour ago, Nickfromwales said: Work out how much surplus you need to routinely dump and do the maths there. Pointless trying to dump a load of excess into a tiny ( 25L ) buffer. In honesty it’s rubbish as in the winter you’ll be lucky to see 25% PV output which will prob be enough to still be pulling from the grid most days ( so no surplus ). PV > heating = ? I was more just thinking about a buffer tank for an ASHP and UFH (Like @joe90 has)... how do you size that? I have been entertaining the idea of adding one, depending on how big it would need to be. The addition of pv is for when I have some more spare cash than I currently have! Link to comment Share on other sites More sharing options...
joe90 Posted November 13, 2020 Share Posted November 13, 2020 29 minutes ago, Gav_P said: I was more just thinking about a buffer tank for an ASHP and UFH (Like @joe90 has If I remember correctly mine is 80 litres. 1 Link to comment Share on other sites More sharing options...
CC45 Posted November 14, 2020 Share Posted November 14, 2020 our buffer tank is 90 litres 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted November 14, 2020 Share Posted November 14, 2020 23 hours ago, joe90 said: If I remember correctly mine is 80 litres. 6 minutes ago, CC45 said: our buffer tank is 90 litres FIGHT!!! 1 1 Link to comment Share on other sites More sharing options...
CC45 Posted November 14, 2020 Share Posted November 14, 2020 (edited) how childish! - you suggested 90litres Nick!!! Edited November 14, 2020 by CC45 update Link to comment Share on other sites More sharing options...
Nickfromwales Posted November 14, 2020 Share Posted November 14, 2020 9 minutes ago, CC45 said: how childish! - you suggested 90litres Nick!!! Lol. I don't actually want you to have a fight ( honest )...... Well, maybe just a little one, and upload to YouTube? 1 Link to comment Share on other sites More sharing options...
CC45 Posted November 15, 2020 Share Posted November 15, 2020 bit of hair pulling and thats it? hardly likely to go viral! Link to comment Share on other sites More sharing options...
oranjeboom Posted November 17, 2020 Author Share Posted November 17, 2020 On 12/11/2020 at 20:41, Onoff said: Seriously, if you want 5L of it, no problem. The clever people on here will say whether it's OK. Cleans up elements a treat. Thanks for the offer. I got some distilled vinegar and that seems to have done the job nicely: After On 13/11/2020 at 19:28, PeterW said: For anyone looking for cheap Wilo pumps for this sort of stuff, Toolstation have got the 5/130 at change of £90 https://www.toolstation.com/wilo-yonos-pico-circulating-pump/p75983 Yes, thanks. I had already purchased from TS as I find the cheaper in 90% of cases. Bought the more expensive version, but not sure what benefit that gives me really. On 13/11/2020 at 19:33, PeterW said: Have you not got any inhibitor in the system ..?? If you are hacking into the system then worth adding one of the mag filters (cheap one here) which you can also use for dosing inhibitor into the loops. Shouldn’t be getting scale on a Willis as it’s a closed loop system. Yes I added some but no room anymore for a mag filter. So with the fact that ScrewFix didn't have any Tectite push fittings and the fact that the family started moaning about no heating on Saturday I re-inserted the cleaned Willis heaters into the original configuration without new pump. They soon started hisssssssssssssssing again which surprised me as they were fine for many months originally. I could have used compression fittings but as it's such a tight fit and the flexi's to the manifold are at different angles and aren't flat to the wall, I splashed the cash for the Tectite fittings (not read great stuff about the Connex fittings from TS. Can't solder in that confined space with the plastic pipe and compressions will keep twisting elsewhere when I make any adjustments I suspect. Anyway, when I get all my fittings from SF I will do as prescribed by @Nickfromwales et al and hope it all behaves again. Link to comment Share on other sites More sharing options...
TerryE Posted November 18, 2020 Share Posted November 18, 2020 (edited) Sorry to be late to this discussion. As you know I have a PHE in parallel to my single Willis, and these are configured in a single loop with my UFH manfold feeds to 3 underfloor loops that are all ~100m. This is a closed system with its own 5L expansion. Can I first suggest that you discount scaling. Surely yours is also a closed system? In my case I've got maybe 40L of water in my system. Top up is manual and I haven't had to do this in ~2½ years of running; still at the 1 bar that I filled it to at commissioning. How much hardness is there in 40L of water? As I've discussed before I have a lot of temperature logging -- 12 digital thermostat sensors that I collect and log every 2 mins since commissioning. My pump is on a medium setting and the single Willis at this flow rate lifts the circulating temperature by roughly 7½ °C though this is mixed with the PHE bypass dropping the overall mixed to around +5°C. So last night the heating came on at around 3:02 AM with the return starting at around 22½°C with the out quickly climbing to 27½°C. This 3kW being dumped into the slab steadily lifted the return temperature to 25.7 °C at 06:38 when the heating was turned off. At each midnight my control system calculates the top up needed for the coming day based on the forecast average external temperature with an adjustment based on the 24hr average house temperature against setpoint. This ~3½ × 3 kWh was what it calculated as needed. Note that my (NodeRED) heating control turns the Willis off at 35°C as a safety limit (keeping the pump circulating) though IIRC the hottest out flow that that I've recorded was just over 31°C. I have my manifold TMV set at 40°C (mainly as a safety backstop) so the valve is in reality always open and any output from the willis is always dumped into the slab. I note that you don't seem to implement any temperature control on your Willis outputs, yet have your TMV set at 35°C. So what happens if your loops cross this threshold? The mixer will start bypassing the UFH loops and now the output from the Willis is on a short closed cycle isolated from the circulating pump and with no heat dump and so you are heating maybe 3L of water with 6kW. No wonder it starts to kettle! IMO, the thermostat cutout on both Willis heaters should be set to a maximum of 35°C (or as in my case I have them in-built Willis sensors at minimum and I use a digital thermostat on the Willis casing for on-off control) and at least say 5°C less than the manifold TMV to ensure that you never short cycle through the Willis heaters. You can't dump 6kW × 24hrs into slab without seriously stressing something. You have to validate your design and assumptions during commissioning otherwise you risk permanent damage. At least with a TMW set at 35°C any damage will be in above ground replaceable components. PS. Adding extra short circuits is only going to make things worse. Edited November 18, 2020 by TerryE 2 Link to comment Share on other sites More sharing options...
oranjeboom Posted November 18, 2020 Author Share Posted November 18, 2020 8 hours ago, TerryE said: Sorry to be late to this discussion. Better late than never! Thanks for the input. 8 hours ago, TerryE said: This is a closed system with its own 5L expansion. Similar to my one loop system too then (except for PHE and distance between the heaters and manifold (1.6m iirc). I have 18L expansion vessel. 1150m (130L) of wunda pipe but currently only heating 800m (90.4L) as one side of the house is not used/finished so 4 loops in the 12 port manifold are shut. 8 hours ago, TerryE said: I note that you don't seem to implement any temperature control on your Willis outputs, yet have your TMV set at 35°C. So what happens if your loops cross this threshold? The mixer will start bypassing the UFH loops and now the output from the Willis is on a short closed cycle isolated from the circulating pump and with no heat dump and so you are heating maybe 3L of water with 6kW. No wonder it starts to kettle! Yes, my setup is entirely manual for now so I'm reliant on the temp setting on the heaters themselves and the manifold TMV. I keep the door open to the 'plant room' so I'm in the habit of checking the temps on the heater outlet pipe and the manifold temp. Not an ideal setup but the plan is to put some controls into the system when I have the time. The Willis' are set now set to around 30oC but are still hissing. I have experimented with the manifold TMV set to fully open and fully closed (well to 30oC setting at least as its range is 30-70oC). Not sure whether it works! So in any case, the heaters are still hissing. I may not have let the inhibitor blend sufficiently into all the loops before I turned on the heaters and now they are partially scaled up again so hiss as soon as i turn them on. May also be worth checking the water hardness in the system? I'm in a very hard area! So perhaps worth taking the bugger's out again and cleaning them up one more time. Then re-insert and make sure manifold TMV is fully open. If they start hissing again, then either the TMV is just causing it to loop round the Willis circuit (faulty TMV?) or there is not sufficient flow and I need to add that pump. I think the temp gauges aren't accurate either (they are different types (one on left has thermometer type rod that's inserted into the pipe fitting (but I suspect that bit of upright pipe has an air pocket)). The one on the right is a clip on type and gives a different reading depending if it's on top of the pipe or the side. 7 And then the Wunda thermometer is also a push in one and I don't know their accuracy, but think the same as yours: . What digital thermostats do you use @TerryE? Ideally I'd need something a bit more accurate as well as something to measure the return flow. And one day be nice if i could all have it logged like you do Terry! 11 hours ago, TerryE said: You can't dump 6kW × 24hrs into slab without seriously stressing something. I don't have it on for more than a few hours at a time, usually 4hrs. The rooms get sufficiently warm (20oC which is fine for me but perhaps not the wife). But yes, I currently have the TMV on full whack (which would permit heat of 70c into the slab) but manifold indicates 28.5. I tried different temp settings on the manifold TMV this afternoon so expected to see a decrease in the manifold temp and increase in the Willis loop (as I reduced the manifold temp setting): So is my manifold buggered? Have I assembled it wrong? Could there be a blockage? Or perhaps there isn't sufficient flow into the TMV and that's why there is no discernible difference in the temps? Worth getting one of these infra-red temp readers (https://www.toolstation.com/draper-infrared-thermometer/p94325)to re-check accuracy of temps? Can't fit the pump or create a separate hydraulic loop for the Willis heaters as SF still haven't delivered my parts so won't take TMV off until I have all parts present! Link to comment Share on other sites More sharing options...
TerryE Posted November 18, 2020 Share Posted November 18, 2020 (edited) As I said, if you don't have a buffer tank, then your slab is your thermal buffer. You mustn't have manifold mixer set below the Willis setpoints. I personally would be uncomfortable without detailed temperature logging to catch any anomalies. I use DS18B20 digital thermos which (when calibrated) are accurate to around ½°C. BTW you can just leave the pump on with no willis heating and the circuits will reach a common temp after a few hours so you can see if you have any measurement offsets. Edited November 18, 2020 by TerryE Link to comment Share on other sites More sharing options...
TerryE Posted November 18, 2020 Share Posted November 18, 2020 2 hours ago, oranjeboom said: The Willis' are set now set to around 30oC but are still hissing. I find this contradictory. Hissing indicates enough turbulence / spot heating to generate acoustic losses, but this shouldn't happen at 30°C. Link to comment Share on other sites More sharing options...
joe90 Posted November 18, 2020 Share Posted November 18, 2020 Can you put a multimeter on the Willis to confirm it’s turning off at 30! ? Link to comment Share on other sites More sharing options...
Gav_P Posted November 18, 2020 Share Posted November 18, 2020 (edited) Is it simply that the water is not circulating? As it worked one way or the other in the past, then it should work now (for a while at least). Assuming that the TMV is open/working then is there anything else that could be blocking the circuit? Edited November 18, 2020 by Gav_P Link to comment Share on other sites More sharing options...
TerryE Posted November 19, 2020 Share Posted November 19, 2020 (edited) 23 hours ago, Gav_P said: Assuming that the TMV is open/working then is there anything else that could be blocking the circuit? This type of TMV setup is primarily designed for a conventional gas boiler which will be outputting at 60°C +, say, also heating upper floor rads and DHW. It operates as an S-plan valve. If the circulating water temp is below the control setpoint, then the TMV routes the hot supply to the manifold out. If above then the manifold return is routed to the out, and the hot supply is isolated. This routing isn't bang-bang but blends over a temperature range. Hence this acts to blend in the 60°C feed into the circulating UFH loops at roughly the setpoint temp. We aren't really doing any of this, and for this Willis-in-the-loop use-case, the TMV is redundant or at best a safety valve to prevent abnormal temperature water at the manifold out. As I said for my configuration and loop flow rates, the 3kW will only give a 5°C step up on the return temperature. 2×Willis should give double this, though I only have 3×100m so my flow resistance will be a higher than Erwin's and so at a medium setting his pump will have a smaller delta, say 6°C. At the moment this delta seems not to be taken or monitored. Edited November 19, 2020 by TerryE Link to comment Share on other sites More sharing options...
oranjeboom Posted November 22, 2020 Author Share Posted November 22, 2020 On 18/11/2020 at 17:33, joe90 said: Can you put a multimeter on the Willis to confirm it’s turning off at 30! ? Will do that in the morning when I will have multimeter. What I did do today was to rig up a sole heater and had it set to 25oC. It soon shot up to 60oC and the safety cut out activated. Why did it not heat to only circa 25oC? Well I guess as there was no flow at all and these things are set up to operate with a minimum flow rate there was no way to regulate the temp with just 600ml water. At least I know the safety cut off works! On 19/11/2020 at 17:58, TerryE said: At the moment this delta seems not to be taken or monitored. No, there's no 'space' on the manifold for a return thermometer at the moment, so I'm planning to 'open' up one of the bars and put the pressure gauge there and place a thermometer in its place. On 18/11/2020 at 18:22, Gav_P said: Is it simply that the water is not circulating? As it worked one way or the other in the past, then it should work now (for a while at least). Assuming that the TMV is open/working then is there anything else that could be blocking the circuit? Water was circulating as the floors were warm. I think it's down to having very hard water (380ppm) and that when I added the inhibitor it didn't distribute through the system sufficiently so may have been getting pockets of pure hard water hitting the elements. I also think the flow rate is too low through the heaters and not being mixed into the UFH manifold sufficiently which would explain the 4.5oC temp difference between manifold and heaters. Tomorrow I'll add the pump and will add some more inhibitor (sentinel x100) into the system and let it distribute for an hour or so before I turn on the heaters. Link to comment Share on other sites More sharing options...
joe90 Posted November 22, 2020 Share Posted November 22, 2020 Frankly shooting past the 25’ and cutting out at 60’ sounds like the stat is kaput, how much are replacements?, is it not worth trying a new one? Link to comment Share on other sites More sharing options...
PeterW Posted November 22, 2020 Share Posted November 22, 2020 3 minutes ago, joe90 said: Frankly shooting past the 25’ and cutting out at 60’ sounds like the stat is kaput, how much are replacements?, is it not worth trying a new one? +1 to that - I would try a decent one like a Backer stat These go down to 15°c and cut out is 65°c so should be fine. https://www.tlc-direct.co.uk/Products/IHST7slashC.html Link to comment Share on other sites More sharing options...
TerryE Posted November 22, 2020 Share Posted November 22, 2020 If you are rising to 60°C then either the manifold pump is not running when the heater is on, and / or the TMV bypass is open short-circuiting the willis path. Is your TMV at min rather than max setting? In my system, NodeRED runs on an RPI but it talks via a USB serial port to a microcontoller which does all of the actual relay control / collect temps. Quite independent for the NodeRED logic, the microcontroller implements some safety rules such as The Willis can only turn on if the pump is running The Willis is turned off if its temp goes above a safety threshold Only one SunAmp can be heating at the same time. Link to comment Share on other sites More sharing options...
dpmiller Posted November 23, 2020 Share Posted November 23, 2020 Just for a sligtly different view... Over here where the Willis is used as intended (soft but dirty water, convective flow only) they kettle away happily for decades, bouncing off the control stat any time they want to. 1 Link to comment Share on other sites More sharing options...
oranjeboom Posted November 23, 2020 Author Share Posted November 23, 2020 11 hours ago, joe90 said: Frankly shooting past the 25’ and cutting out at 60’ sounds like the stat is kaput, how much are replacements?, is it not worth trying a new one? I think it works fine. I may get another one today but I expect it would do the same - ie easily overshoot the target temp in a static low volume water. 11 hours ago, PeterW said: +1 to that - I would try a decent one like a Backer stat These go down to 15°c and cut out is 65°c so should be fine. https://www.tlc-direct.co.uk/Products/IHST7slashC.html The one that they come with are Tesla UK ones TS225 https://www.unventedcomponentseurope.com/tesla-11-control-high-limit-rod-thermostat-for-immersion-heaters-dual-thermostat.html which operates up to "give a water temperature of approx 60oC" as per supplied generic instructions (though the model fitted is 25-70oC). But yeah 15°c to 65°c would be better for UFH. 9 hours ago, TerryE said: If you are rising to 60°C then either the manifold pump is not running when the heater is on, and / or the TMV bypass is open short-circuiting the willis path. Is your TMV at min rather than max setting? Just tested it in 600ml of water Terry! No circulation. Not connected to anything. Link to comment Share on other sites More sharing options...
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