JohnMo Posted September 29 Share Posted September 29 14 hours ago, marshian said: WC comp wouldn’t work with all the TRV heads removed Yes it would. WC really doesn't need anything in the house except a balanced heating system. 14 hours ago, marshian said: boiler doesn’t know whats going on outside it’s flow and return temp and the volume of water passing thro it That's the thing with weather comp, it doesn't need any more info, just outside temp to set target flow temperature against the defined curve. In fact all the boiler is interested in target flow temperature and return temperature. It then modulates output based on management of dT, it doesn't even even care about flow rate unless it actually modulates flow rate. Link to comment Share on other sites More sharing options...
marshian Posted September 29 Author Share Posted September 29 16 minutes ago, JohnMo said: Yes it would. WC really doesn't need anything in the house except a balanced heating system. You are taking what I said out of context - yesterday "specifically" the boiler wouldn't work (so WC wouldn't work too) with all the TRV heads removed (I tried that in case it was a flow issue) Link to comment Share on other sites More sharing options...
marshian Posted October 8 Author Share Posted October 8 As I had to have the floor up in the room above the kitchen (where boiler is on an external wall) to run a 3 core cable from Circ pump in the airing cupboard (centre of the house) I looked at the flow and return pipes and decided now was the time to break up the twins so to speak (roughly 2 x 4m of 22 mm copper pipework run bang along side each other (with the traditional nails bent over to hold them in place) New pipework is far enough apart to allow 19mm of insulation around them - annoyingly I don't have enough spare 22mm lagging so that'll need to get ordered asap - just waiting on the gas engineer to come and connect up the pump to boiler wire. Still waiting on a resolution for the HWD/Weather comp situation so running it manually as temps start to get colder. I am absolutely amazed at how stable the flow temps are at 30 Deg and the length of the burns at very low boiler output. SWIMBO is less inclined to comment about the "cold rads" if the house is a comfortable temperature Bodes well for for my estimations that 1.4 slope would probably be a bit high but if I adopted a 24/7 approach I could go as low as 0.8 - but I think we will end up with 1.0 to 1.2 bearing in mind we heat intermittently as the house insulation overall isn't good enough yet. Hopefully the process can move forward again soon - I am mildly miffed that I'm still having to manually change boiler temps for HW and CH but I feel it's moving in the right direction Link to comment Share on other sites More sharing options...
marshian Posted October 10 Author Share Posted October 10 Update time Friday afternoon the gas engineer is making another visit - hopefully we will have the system running as it should by the end of the day........... FLW!!! Link to comment Share on other sites More sharing options...
Lofty718 Posted October 10 Share Posted October 10 I run a curve of 0.25 for rads and 0.2 for UFH, over 1 is very high Link to comment Share on other sites More sharing options...
marshian Posted October 10 Author Share Posted October 10 20 minutes ago, Lofty718 said: I run a curve of 0.25 for rads and 0.2 for UFH, over 1 is very high What's your heat loss at -2? Link to comment Share on other sites More sharing options...
marshian Posted October 10 Author Share Posted October 10 1 hour ago, Lofty718 said: I run a curve of 0.25 for rads and 0.2 for UFH, over 1 is very high I've just looked at the curves for the boiler at 0.2 slope Outside temps and boiler flow temps is in the table below Outside / Flow temp 20 - 20 15 - 22 10 - 23 5 - 24 0 - 25 -5 - 26 Mighty impressive - I'd have to rebuild the house to achieve that - I think I'll be doing really well to get down to 1.0 Link to comment Share on other sites More sharing options...
Lofty718 Posted October 11 Share Posted October 11 The curves on Viessmann must be different, my flow temps are a fair bit higher than that. Always between 26-40 1 Link to comment Share on other sites More sharing options...
marshian Posted October 11 Author Share Posted October 11 7 hours ago, Lofty718 said: The curves on Viessmann must be different, my flow temps are a fair bit higher than that. Always between 26-40 Viessmann curves below Link to comment Share on other sites More sharing options...
JohnMo Posted October 11 Share Posted October 11 Lucky you only have one set of curves, our Atag boiler, had one set of curves if you used their controller, very similar to Viessmann. If you didn't use the controller the boiler had a different set of curves you could use which are numbered differently and start at different temps, ranging from 20 degs to 26 degs flow temp at 20 deg OAT. Link to comment Share on other sites More sharing options...
marshian Posted October 11 Author Share Posted October 11 29 minutes ago, JohnMo said: Lucky you only have one set of curves, our Atag boiler, had one set of curves if you used their controller, very similar to Viessmann. If you didn't use the controller the boiler had a different set of curves you could use which are numbered differently and start at different temps, ranging from 20 degs to 26 degs flow temp at 20 deg OAT. Sounds like that would screw with your head!!! Link to comment Share on other sites More sharing options...
marshian Posted October 11 Author Share Posted October 11 Anyway system now drained down (again........) I'm ready whenever he finishes his current job Might turn off the water and replace an iffy isolation valve (been on the list for a while) Link to comment Share on other sites More sharing options...
marshian Posted October 11 Author Share Posted October 11 And back to a dumb boiler again Pump wired directly to the boiler (so it has control) still getting 75 fault codes so that was a lot of effort for no gain HWD box reactivated - worked brilliantly - fired up the boiler and ramped up the power - tank of HW generated in 25 mins Switched over to CH in weather compensated mode - and the bloody boiler thinks it's still doing HW so instead of a 37 deg flow temp it goes straight for 80 deg........... On the positive side new pipework for flow and return to the airing cupboard is all done so at least I can put the floor back down Link to comment Share on other sites More sharing options...
marshian Posted October 12 Author Share Posted October 12 And the best bit tonight I've established that in the current configuration giving the boiler control of the pump means it runs 24/7 regardless of a call for heat!!! Link to comment Share on other sites More sharing options...
marshian Posted October 18 Author Share Posted October 18 (edited) Right I'm resigned to sorting out the control side of the boiler myself HW demand is now working fine - ramps up temp and modulation and tops up a tank of water to 55 deg in 15 mins so no issues there The problems I have are I can't find a wiring diagram where a NO valve is used for CH and a NC valve is used for HW Often X plans are on boilers where HW/CH selection is done with 2 switched lives Closest I can find is However whilst it gives some valve wiring options it doesn't cover the X plan set up I don’t have an NTC sensor (Shown as Cylinder limit Thermostat) so ignore that The HW tank supply has the 2 port Normally Closed valve NC Valve has 5 Wires Live (Brown), Neutral (Blue), Earth (Yellow/Green), Grey (Live feed for the internal Switch) and Orange (240V output when valve is fully open) The CH supply feed has a 2 Port Normally Open Valve NO valve has 3 Wires Live Brown), Neutral (Blue) and Earth (Yellow/Green) I've set that side up so when the Cyl Stat calls for heat the brown “Live” powers up the Normally Closed Valve to Open (the grey wire has permanent power but it only goes to an internal switch that makes when the valve is fully open and puts 240v to the Orange – the power from that goes to the Cylinder demand box to tell the boiler it it’s doing HW – it ramps up to 80 deg C and modulates as high as it can based on return temps to heat the HW cylinder (coil) to the target stat temp in the shortest time possible The same signal Live also powers the Brown for the Normally Open Zone valve for heating so it closes stopping elevated temp HW going round the CH circuit As soon as the tank stat is satisfied the live circuit to the zone valve is removed, the HW zone valve closes, the CH zone valve opens – the Live feed to the HW demand box is removed and the boiler reverts to weather compensated flow temps The only other issue on the HW side is if the HW tank stat picks up a significant drop in temp (the hysteresis is quite broad) then without anything being on the HW valve will open and the CH valve will close and the pump will start so I think I have a wiring issue in either wiring centre, Heating controller or very possibly Boiler. Edited October 18 by marshian Link to comment Share on other sites More sharing options...
John Carroll Posted October 18 Share Posted October 18 2 hours ago, marshian said: Right I'm resigned to sorting out the control side of the boiler myself HW demand is now working fine - ramps up temp and modulation and tops up a tank of water to 55 deg in 15 mins so no issues there The problems I have are I can't find a wiring diagram where a NO valve is used for CH and a NC valve is used for HW Often X plans are on boilers where HW/CH selection is done with 2 switched lives Closest I can find is However whilst it gives some valve wiring options it doesn't cover the X plan set up I don’t have an NTC sensor (Shown as Cylinder limit Thermostat) so ignore that The HW tank supply has the 2 port Normally Closed valve NC Valve has 5 Wires Live (Brown), Neutral (Blue), Earth (Yellow/Green), Grey (Live feed for the internal Switch) and Orange (240V output when valve is fully open) The CH supply feed has a 2 Port Normally Open Valve NO valve has 3 Wires Live Brown), Neutral (Blue) and Earth (Yellow/Green) I've set that side up so when the Cyl Stat calls for heat the brown “Live” powers up the Normally Closed Valve to Open (the grey wire has permanent power but it only goes to an internal switch that makes when the valve is fully open and puts 240v to the Orange – the power from that goes to the Cylinder demand box to tell the boiler it it’s doing HW – it ramps up to 80 deg C and modulates as high as it can based on return temps to heat the HW cylinder (coil) to the target stat temp in the shortest time possible The same signal Live also powers the Brown for the Normally Open Zone valve for heating so it closes stopping elevated temp HW going round the CH circuit As soon as the tank stat is satisfied the live circuit to the zone valve is removed, the HW zone valve closes, the CH zone valve opens – the Live feed to the HW demand box is removed and the boiler reverts to weather compensated flow temps The only other issue on the HW side is if the HW tank stat picks up a significant drop in temp (the hysteresis is quite broad) then without anything being on the HW valve will open and the CH valve will close and the pump will start so I think I have a wiring issue in either wiring centre, Heating controller or very possibly Boiler. This may be of some help?. HW Priority Diagram.pdf 1 Link to comment Share on other sites More sharing options...
marshian Posted October 18 Author Share Posted October 18 Indeed it is - thank you sir One issue I see is that it uses a relay arrangement which I'm trying to avoid as I think it's not needed with a NO CH valve and a NC HW valve That diagram uses 2 NC Valves for CH and HW (hence the linking of the two oranges to energise boiler and pump) But It gives me a start that is slightly easier for me to get my head round than the Viessmann diagram (which I find really complicated) Not sure the world is ready for how far I've got (not complete) drawing up the X plan with crayons (to the same format as the std Wago (L16 wiring centre) but I'll share it so you can laugh Link to comment Share on other sites More sharing options...
scottishjohn Posted October 18 Share Posted October 18 On 29/09/2024 at 10:51, JohnMo said: Yes it would. WC really doesn't need anything in the house except a balanced heating system. have you balanced all the rads ? eg 2probe thermometer one on inlet to rad and one on return wide tvr right open and let it run then adjust flow on other side of rad so you get biggest temp drop across the rads the pump will naturally pump to easiest path -so this will make it balance output in all rads in an ideal world you are looking for 20c drop across the rad - unlikely you wil get this . but if rads are incorrect size it will be even worse from looking at your first post it si shouting at me that your insulation levels are very very poor # 12" of loft inmsualtion is absolute minimum or a better oproduct that will give that levle in a THINNER LAYER this is hwere you should be spending money as insulation is a once only cost you seem to be blaming it all onthe boiler . Idid a test in old house i had with an ir temp gun ,which i used at work on race cars - checked wall temp ,then moved a piicture sideways on the wall and checked again --it was 4c lower which told me my wall insulation was crap the easiest solution was to fit all ouside walls with insulated plaster board 50mm thick -no need to remove exsisting --just dot +dab fix it If youo want to get exotic ,buy a flur gun which will show cold ppatchs everywhere and high light air leaks etc Link to comment Share on other sites More sharing options...
MrPotts Posted October 18 Share Posted October 18 23 minutes ago, marshian said: Indeed it is - thank you sir One issue I see is that it uses a relay arrangement which I'm trying to avoid as I think it's not needed with a NO CH valve and a NC HW valve That diagram uses 2 NC Valves for CH and HW (hence the linking of the two oranges to energise boiler and pump) But It gives me a start that is slightly easier for me to get my head round than the Viessmann diagram (which I find really complicated) Not sure the world is ready for how far I've got (not complete) drawing up the X plan with crayons (to the same format as the std Wago (L16 wiring centre) but I'll share it so you can laugh In an arrangement where you have NC and NO valves the NC HW valve controls the NO CH valve. You just connect the orange of the NC valve to the brown of the NO valve. Link to comment Share on other sites More sharing options...
marshian Posted October 18 Author Share Posted October 18 (edited) 23 minutes ago, scottishjohn said: have you balanced all the rads ? eg 2probe thermometer one on inlet to rad and one on return wide tvr right open and let it run then adjust flow on other side of rad so you get biggest temp drop across the rads the pump will naturally pump to easiest path -so this will make it balance output in all rads in an ideal world you are looking for 20c drop across the rad - unlikely you wil get this . but if rads are incorrect size it will be even worse from looking at your first post it si shouting at me that your insulation levels are very very poor # 12" of loft inmsualtion is absolute minimum or a better oproduct that will give that levle in a THINNER LAYER this is hwere you should be spending money as insulation is a once only cost you seem to be blaming it all onthe boiler . Idid a test in old house i had with an ir temp gun ,which i used at work on race cars - checked wall temp ,then moved a piicture sideways on the wall and checked again --it was 4c lower which told me my wall insulation was crap the easiest solution was to fit all ouside walls with insulated plaster board 50mm thick -no need to remove exsisting --just dot +dab fix it If youo want to get exotic ,buy a flur gun which will show cold ppatchs everywhere and high light air leaks etc I can't work out how to split up a long list of questions into individual responses so see below Yes (EB4 TRV bodies) and flow rates are suitable for lower flow temps When all rads in circuit - flow rate is about 1.1 m3/hr When TRV's start to cut in it drops down to around 0.5 m3/hr I'm not looking for 20 deg drop across any of my rads at a flow temp of 37 deg C - it would be impossible - the return temp would be less than the room target (or actual temp) Using heat geek table is a better guide to expected drop across the rads (or diff between flow and return) Flow Temp Return Temp Diff 55 38.5 16.5 50 35.0 15.0 45 31.5 13.5 40 28.0 12.0 35 24.5 10.5 Rads are sized to the rooms and all but one room they are oversized for the flow temps currently being used I'm not blaming anything on the boiler - I'm seriously impressed with the Viessmann 100-W "Heat only" - But I do have some control issues which I am working thro Done IR wall floor and ceiling checks - this thread is not about heat loss or improving it - I know what I need to do there and it comes after boiler control issues are sorted Edited October 18 by marshian Layout Link to comment Share on other sites More sharing options...
MrPotts Posted October 18 Share Posted October 18 Good video here…….. Link to comment Share on other sites More sharing options...
marshian Posted October 18 Author Share Posted October 18 Just now, MrPotts said: Good video here…….. It is a good video But "Ideal Vogue" use 2 switched lives Link to comment Share on other sites More sharing options...
marshian Posted October 18 Author Share Posted October 18 10 minutes ago, MrPotts said: In an arrangement where you have NC and NO valves the NC HW valve controls the NO CH valve. You just connect the orange of the NC valve to the brown of the NO valve. I need a feed to go to the HW Demand box Putting Brown to Brown works and keeps the HW demand part simple CH in normal operation the NO valve is consuming no power and idle When HW is demanded - NC HW Valve and NO CH Valve share the Brown so both effectively energise CH Closes from Open HW Opens from closed Why wouldn't that be OK? Link to comment Share on other sites More sharing options...
MrPotts Posted October 18 Share Posted October 18 43 minutes ago, marshian said: It is a good video But "Ideal Vogue" use 2 switched lives If you watch through the video he describes how to convert an s plan to PDHW with a NO valve. Link to comment Share on other sites More sharing options...
MrPotts Posted October 18 Share Posted October 18 38 minutes ago, marshian said: I need a feed to go to the HW Demand box Putting Brown to Brown works and keeps the HW demand part simple CH in normal operation the NO valve is consuming no power and idle When HW is demanded - NC HW Valve and NO CH Valve share the Brown so both effectively energise CH Closes from Open HW Opens from closed Why wouldn't that be OK? Use the switched live orange from the NC valve to apply power to the NO valves live connection. Then when there is a call for HW the NC HW valve will apply live to the NO CH valve thus closing it. Link to comment Share on other sites More sharing options...
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