ProDave Posted July 23, 2022 Share Posted July 23, 2022 ^^^ Peter's post above also shows it is the left hand thermostat that is the cylinder thermostat for the boiler, and that is the one you want to turn down to a lower temperature, say 50 degrees. (the right hand one is the thermostat for the immersion heater) So run the system so the hot water is on. Turn that left thermostat down until it clicks, then the boiler and the pump should stop. If it does that, then chances are it is wired correctly. You should also hear the motorised valve spring shut when the thermostat clicks off. The cylinder thermostat should always be set lower than the boiler flow temperature. Link to comment Share on other sites More sharing options...
Barryscotland Posted July 23, 2022 Author Share Posted July 23, 2022 41 minutes ago, ProDave said: ^^^ Peter's post above also shows it is the left hand thermostat that is the cylinder thermostat for the boiler, and that is the one you want to turn down to a lower temperature, say 50 degrees. (the right hand one is the thermostat for the immersion heater) So run the system so the hot water is on. Turn that left thermostat down until it clicks, then the boiler and the pump should stop. If it does that, then chances are it is wired correctly. You should also hear the motorised valve spring shut when the thermostat clicks off. The cylinder thermostat should always be set lower than the boiler flow temperature. presuming the bottom left red dial is stat boiler is wired through as did as you suggested, had hot water on demand and turned dial when on 3 the zone valve clicked and when got to the boiler it was off so presume it is wired properly and that the problem is the stat is set too high? Anybody no what temps the 1 2 3 4 5 relate to? Link to comment Share on other sites More sharing options...
kommando Posted July 23, 2022 Share Posted July 23, 2022 Googling Cotherm type TSE got me to Link to comment Share on other sites More sharing options...
ProDave Posted July 23, 2022 Share Posted July 23, 2022 The red dial in the middle of the blue round thing is the immersion heater thermostat, NOT the cylinder stat for the boiler. That should make no difference to the heating. Yours appears to be wired / constructed differently to the manual @PeterW posted. you have TWO tank thermostats for the boiler. They are both mounted in that metal plate at the top. The right hand one has a dial 1,2,3,4,5 and that is the cylinder thermostat that will shut off the boiler when the tank gets up to temperature. It currently looks to be set to setting 4. that is the one you want to turn down while it is running to see if the boiler then shuts off. The other one to the left is the safety cut out. In the event of the main thermostat failing and the water getting too hot, that will trip and the red button will pop out. You can usually reset that by pushing the red button in again. Link to comment Share on other sites More sharing options...
ProDave Posted July 23, 2022 Share Posted July 23, 2022 Further thought: If turning down the red thermostat in the blue round thing really did shut off the boiler then the electrician has messed up and got the immersion and control cables the wrong way round. Please confirm exactly which thermostat does turn the boiler on and off and until you have done that, do not try turning the immersion heater switch on. Link to comment Share on other sites More sharing options...
Barryscotland Posted July 23, 2022 Author Share Posted July 23, 2022 14 minutes ago, ProDave said: Further thought: If turning down the red thermostat in the blue round thing really did shut off the boiler then the electrician has messed up and got the immersion and control cables the wrong way round. Please confirm exactly which thermostat does turn the boiler on and off and until you have done that, do not try turning the immersion heater switch on. I’ve never used the immersion since we moved in so no idea if it works, it was the red dial that I turned down and boiler clicked of so unless it was just coincidence there may be an issue. I’ve phoned sparky that did the wiring up of it and he’s calling in Monday to check it. Left a message for plumber for any certs I need Link to comment Share on other sites More sharing options...
PeterW Posted July 23, 2022 Share Posted July 23, 2022 Looking at that cable he hasn’t even wired it correctly. All the white connections should have wires in them - looking at that, he’s ignored those stats and I think he’s avoided all the controls…. @Barryscotland can you get a photo of the white connector so I can see what wires go into the bottom of which connection ..? Link to comment Share on other sites More sharing options...
PeterW Posted July 23, 2022 Share Posted July 23, 2022 2 hours ago, ProDave said: Yours appears to be wired / constructed differently to the manual @PeterW posted. without the model number I had to guess the generic Megaflo indirect installation manual. Link to comment Share on other sites More sharing options...
ProDave Posted July 23, 2022 Share Posted July 23, 2022 Well double check and see if turning that back up again turns the boiler back on? You see there are 2 white cables coming out of the bottom of your grey box on the tank. Follow the left hand one very carefully, (they are cable tied together) and tell me if it goes into the switch on the wall or the rectangular box on the wall below it? No criticism intended @PeterW for not getting exactly the correct manual. S plan wiring with 2 port valves does not need hot water off, that's only Y plan with a 3 port mid position, so only using 2 connections from the thermostat is not necessarily "wrong" Link to comment Share on other sites More sharing options...
Barryscotland Posted August 9, 2022 Author Share Posted August 9, 2022 So sparky and plumber both came out, water out the hot tap was 82 degrees according to the sparkys thermometer so he did something at the thermostat and boiler has since started cutting out on its own after about 25 minutes and plumber recharged or set something in the cylinder that had gone wrong he says due to the heat of the water, since he’s done that there is no water running out of the copper pipe that goes outside when the boiler runs. Also the showers seem to be back to original pressure. So all is now good, should hopefully use less gas and can get the solar diverter wired in. Link to comment Share on other sites More sharing options...
PeterW Posted August 9, 2022 Share Posted August 9, 2022 12 minutes ago, Barryscotland said: gone wrong he says due to the heat of the water, since he’s done that there is no water running out of the copper pipe that goes outside when the boiler runs. really need to find a new plumber ….. the MegaFlo has an air bubble trapped at the top to maintain pressure and expansion. Sounds like it has been depleted (which the water temperature has nothing to do with) and he’s just recharged it. Should be a Schraeder valve on the top of the tank under a cover - can easily check it is set to 3 Bar with a standard car tyre pressure gauge. Link to comment Share on other sites More sharing options...
Barryscotland Posted August 9, 2022 Author Share Posted August 9, 2022 6 hours ago, PeterW said: really need to find a new plumber ….. the MegaFlo has an air bubble trapped at the top to maintain pressure and expansion. Sounds like it has been depleted (which the water temperature has nothing to do with) and he’s just recharged it. Should be a Schraeder valve on the top of the tank under a cover - can easily check it is set to 3 Bar with a standard car tyre pressure gauge. In hindsight we wouldn’t use the plumber again as we’ve had a few leaks causing plasterboard an paint damage and I have concerns about the lack of pipe fixings used throughout, only used about 2/3 of the ufh pipe the design specified, wouldn’t solder insisted on using the expensive crimp fittings when I already had solder fittings, plumbed a toilet to the wrong position which wasn’t noticed until after the wall was tiled and a good few other things but he was the one the main contractor usually worked with so went with him. Link to comment Share on other sites More sharing options...
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