Hi all,
I moved in to my current house about a year ago. I'm by no means familiar with heating / plumbing systems however I'm generally pretty handy and pick things up quickly. My heating system needs some minor modifications before the Winter really sets in. I have spent the last week of evenings reading up on types of heating system, standard wiring / control plans etc so think I understand how the current system is working (or not).
First things first the current system was installed circa 1991 with only minor modifications over the years. I actually have documents showing the 'as installed' wiring and plumbing which I attach here:
I'm very lucky that the original owner of the house created this documentation for his wife before he passed away.
From what I can make out the system is along the lines of an S-Plan setup. Modifications to these documented designs which I know have taken place (due to notes in the manual and confirmed via observation): MV1 - Cylinder and MV6 - Hall Radiator have both been removed - the motor has been taken off of the valve block and the valve left manually open. I believe this was due to an overheat caused by a relay failure which caused the water to boil and blow to the expansion tank (according to notes in the manual).
Control is via a switch panel which looks like something taken off the set of a 70's episode of Dr Who. It has a couple of ancient digital timer modules but these don't work so I have to either turn the system and zones on or off manually.
Problems I have with this system:
1) The timer(s) don't work properly and can't easily be directly replaced with a standard timer.
2) There is no provision for over-run. The boiler manual (Potterton 50e) shows that the pump should be connected to the pump output on it's wiring terminals - as you can see from the wiring diagram it is not. Also the boiler is not permanently live with heat demanded by the switched live terminal as per the boiler manual directions for a fully pumped system - instead it looks like the live boiler's main live terminal is switched (and there is a wire link from the boiler permanent live terminal in to the switched live terminal).
3) The system is overly complex. Too many thermostats and valves for a small 3 bedroom house. Old relays and valves are bound to fail at some point. There are three different zone/room thermostats within a 2m radius of each other which is really not necessary as the doors between these rooms are rarely closed.
4) There is no bypass in place (as specified by the boiler manual). The fact that the cylinder coil and hall radiator valves are permanently open kind of compensates for this at the moment.
5) As it stands there is no way to heat the hot water without the hall radiator being on too - not a massive problem now but terrible in warmer weather. There is a heating element on the water tank but as of yet I haven't worked out whether this is operational or not.
6) In the current setup the boiler flicks on/off every 5-10 mins even when it doesn't seem like the room thermostats are demanding it. I suspect the cylinder stat is requesting heat to maintain the HW temp at an absolute value which seems unnecessary. Without a timed HW circuit it seems unavoidable as currently setup.
I plan to have a new combi-boiler fitted in the Garage next spring/summer. I would just have the gas hooked up and then completethe plumbing element myself through the summer. That said it will depend on funds so this system might have to see us through a couple of years.
What do I want to do:
1) Simplify - remove all the zones and thermostats scattered about.
2) Add a modern timer/thermostat - ideally Hive.
3) Be able to run the hot water without the radiators in the spring/summer.
I think I have worked out what the simplest way to do this will be but I really need a sanity check on this from someone with experience. What I'm looking at is pretty much turning this in to a standard S-Plan setup with a couple of small differences.
1) Remove all existing valve motors and manually turn the valves to open.
2) Remove all current wiring (I may re-use some of the wire runs but disconnect everything).
3) Install a two-way valve (HW4043H?) on the heating feed side - on the pipe just above 'from gas meter' text on the plumbing diagram above.
4) Wire up boiler, cylinder stat and Hive timer/controller as per standard S-Plan. The only difference being that I will not actually connect a valve for the cylinder - instead leave that permanently open as it is now. I think I'll need to run the 'demand for hot water' output of the timer/controller to the boiler switched live via the cylinder stat? I'd leave the immersion heater element disconnected for now.
5) Install TRVs on the hall and bedroom radiators to allow some manual zoning/control.
I've thought this through and it seems to work in theory but I would like to check a few things:
- I don't mind that the hot water circuit will always be on when the heating is on - it probably does mean that the hot water temperature can't be controlled as well as would be desired but that's currently the case and it doesn't cause a problem (the boiler is only set to '2'). Are there any potential problems here?
- I'm thinking that the cylinder circuit always being open should act as the 'bypass' in theory? Re-plumbing to add a bypass or set up the bathroom radiator as a bypass looks like a big hassle (pipes are under the floor etc).
- If the above isn't safe, I could also potentially not add the new 2-way valve, put TRVs on all radiators which I could close off in the summer/spring. I guess I would then wire both the heating demand and hot water demand (via clinder stat) to the boiler switched live. In this way when the boiler comes on for hot water in the summer - the one-pipe circuit for the bedrooms plus the cylinder circuit would both act as a bypass. Not ideal as the pipes would still heat the house a bit but better than it currently is with the hall radiator blasting away.
- Anything else I'm obviously missing?
Sorry that this seems to have turned in to a massive post - I wanted to ensure I include all of the info that I can. Hofefully a couple of people have the patience to read through it all!
I moved in to my current house about a year ago. I'm by no means familiar with heating / plumbing systems however I'm generally pretty handy and pick things up quickly. My heating system needs some minor modifications before the Winter really sets in. I have spent the last week of evenings reading up on types of heating system, standard wiring / control plans etc so think I understand how the current system is working (or not).
First things first the current system was installed circa 1991 with only minor modifications over the years. I actually have documents showing the 'as installed' wiring and plumbing which I attach here:
I'm very lucky that the original owner of the house created this documentation for his wife before he passed away.
From what I can make out the system is along the lines of an S-Plan setup. Modifications to these documented designs which I know have taken place (due to notes in the manual and confirmed via observation): MV1 - Cylinder and MV6 - Hall Radiator have both been removed - the motor has been taken off of the valve block and the valve left manually open. I believe this was due to an overheat caused by a relay failure which caused the water to boil and blow to the expansion tank (according to notes in the manual).
Control is via a switch panel which looks like something taken off the set of a 70's episode of Dr Who. It has a couple of ancient digital timer modules but these don't work so I have to either turn the system and zones on or off manually.
Problems I have with this system:
1) The timer(s) don't work properly and can't easily be directly replaced with a standard timer.
2) There is no provision for over-run. The boiler manual (Potterton 50e) shows that the pump should be connected to the pump output on it's wiring terminals - as you can see from the wiring diagram it is not. Also the boiler is not permanently live with heat demanded by the switched live terminal as per the boiler manual directions for a fully pumped system - instead it looks like the live boiler's main live terminal is switched (and there is a wire link from the boiler permanent live terminal in to the switched live terminal).
3) The system is overly complex. Too many thermostats and valves for a small 3 bedroom house. Old relays and valves are bound to fail at some point. There are three different zone/room thermostats within a 2m radius of each other which is really not necessary as the doors between these rooms are rarely closed.
4) There is no bypass in place (as specified by the boiler manual). The fact that the cylinder coil and hall radiator valves are permanently open kind of compensates for this at the moment.
5) As it stands there is no way to heat the hot water without the hall radiator being on too - not a massive problem now but terrible in warmer weather. There is a heating element on the water tank but as of yet I haven't worked out whether this is operational or not.
6) In the current setup the boiler flicks on/off every 5-10 mins even when it doesn't seem like the room thermostats are demanding it. I suspect the cylinder stat is requesting heat to maintain the HW temp at an absolute value which seems unnecessary. Without a timed HW circuit it seems unavoidable as currently setup.
I plan to have a new combi-boiler fitted in the Garage next spring/summer. I would just have the gas hooked up and then completethe plumbing element myself through the summer. That said it will depend on funds so this system might have to see us through a couple of years.
What do I want to do:
1) Simplify - remove all the zones and thermostats scattered about.
2) Add a modern timer/thermostat - ideally Hive.
3) Be able to run the hot water without the radiators in the spring/summer.
I think I have worked out what the simplest way to do this will be but I really need a sanity check on this from someone with experience. What I'm looking at is pretty much turning this in to a standard S-Plan setup with a couple of small differences.
1) Remove all existing valve motors and manually turn the valves to open.
2) Remove all current wiring (I may re-use some of the wire runs but disconnect everything).
3) Install a two-way valve (HW4043H?) on the heating feed side - on the pipe just above 'from gas meter' text on the plumbing diagram above.
4) Wire up boiler, cylinder stat and Hive timer/controller as per standard S-Plan. The only difference being that I will not actually connect a valve for the cylinder - instead leave that permanently open as it is now. I think I'll need to run the 'demand for hot water' output of the timer/controller to the boiler switched live via the cylinder stat? I'd leave the immersion heater element disconnected for now.
5) Install TRVs on the hall and bedroom radiators to allow some manual zoning/control.
I've thought this through and it seems to work in theory but I would like to check a few things:
- I don't mind that the hot water circuit will always be on when the heating is on - it probably does mean that the hot water temperature can't be controlled as well as would be desired but that's currently the case and it doesn't cause a problem (the boiler is only set to '2'). Are there any potential problems here?
- I'm thinking that the cylinder circuit always being open should act as the 'bypass' in theory? Re-plumbing to add a bypass or set up the bathroom radiator as a bypass looks like a big hassle (pipes are under the floor etc).
- If the above isn't safe, I could also potentially not add the new 2-way valve, put TRVs on all radiators which I could close off in the summer/spring. I guess I would then wire both the heating demand and hot water demand (via clinder stat) to the boiler switched live. In this way when the boiler comes on for hot water in the summer - the one-pipe circuit for the bedrooms plus the cylinder circuit would both act as a bypass. Not ideal as the pipes would still heat the house a bit but better than it currently is with the hall radiator blasting away.
- Anything else I'm obviously missing?
Sorry that this seems to have turned in to a massive post - I wanted to ensure I include all of the info that I can. Hofefully a couple of people have the patience to read through it all!
