Potterton Statesman Flowsure Re-configured

[casparcat]

I have had the same sort of long running problems with the DHW side of a Potterton Statesman Flowsure (not the "plus") as many others and have decided to take the advice of Gasguru from some years back and take off the plate heat exchanger and re-configure the boiler as a conventional S Plan CH and DHW tank system. While Gasguru indicated that re-wiring was potentially easy, he gave no details. The Flowsure is effectively wired as W Plan with a 3-way diverter valve, so only potentially provides one live terminal for one of the 2 x S Plan two port valves to get power from.

Has anyone got experience of doing this and can even provide a re-wiring guide, as there are potentially four thermostats involved and a DHW flow switch within the Flowsure facia/PCB (I do have a wiring diagram).

As the revised system is also intended to give CH behind a Solar Thermal hot water system, I am also considering keeping a Plate Heat Exchanger on the Solar Thermal side, using the thermal store tank as pre-heat before or after the Plate Heat Exchanger.

Any/all advice welcomed.

 

[oilhead]

Forget the existing wiring. Connect the Burner L/N/E to the limit stat and control stat, which in turn you bring to a wiring block in the boiler.
The live feed to the boiler will be fed by the orange wires from your zone valves. The zone valves will be operated by a switched live from your thermostats, which in turn will be fed by a separate clock.( or programmable stats)

 

[Gasguru]

Wire it as the system boiler...see the manual.

 

[casparcat]

Wire it as the system boiler...see the manual.

Many thanks for that - sadly, the "Installation Instructions" that came with the boiler is a "booklet" rather than a manual and only includes the one Flowsure wiring diagram - for the way Baxi designed it as a combi - no alternative diagram for use as a "system boiler" - which I assume has a variation on the Flowsure name(s) to denote the lack of Plate Heat exchanger assembly?

At least the diagram gives me basic information on wires to the warning lights from the Boiler Stat and the Limit stat/Boiler L1 plus their interrelated connections.

Looks like it's back to paper and coloured crayons to get my head round oilhead's advice for a conventional S Plan re-wire, that will take in the "Pump overrun stat" on the CH circuit plus the "Flow Switch" and "DHW Thermostat" on the DHW circuit, not to mention the facia warning lights!

 

[oilhead]

You can forget the flow switch and anything to do with DHW circuits. You will have no diverter valve connections to worry about.
Take your crayons and draw your own diagrams, OR pay someone to do the job for you

 

[casparcat]

....
Take your crayons and draw your own diagrams, OR pay someone to do the job for you

.....

My experience with electricians and central heating controls has been mixed. If they have a manufacturer's "standard" wiring diagram it's OK, but I have found that, for example their knowledge of what's actually going on inside the zone valves can be limited, so my crayons may well be needed as a starting point.

However, having been made to find my specs (nothing wrong with my eyes - arms just too short) and read the wiring diagram properly, I have been pleased to note that, for once, Baxi have actually used a conventional 6-way wiring block behind the Flowsure's built-in timer clock, so I can take their clock out and re-wire to the 6-way block to take feeds from the conventional S Plan 10-way terminals 1, 2, 4 & 6.

Thanks for your help in forcing an engage of brain.

 

[oilhead]

If you are removing the plate heat exch., then you will also be removing the diverter valve, so you can forget about its wiring. You will take the flow direct from the pump to the heating flow. To make it easy, then you can leave the diverter valve in place, take off the head, open it to heating amd cap the DHW port. Wiring the burner through the control and limit stats gives you a system boiler. Feed the live from your S plan junction box. You won't need too many crayons!!!

 

[casparcat]

You won't need too many crayons!!!

Thanks for the additional information. I have managed to locate the wiring diagram you referred to earlier - page 29 on:

http://www.acwilgar.co.uk/Boiler-Ma...ystem_L-Flowsure_L-FlowsurePlus_L_Install.pdf

For those that want to see it, I will (try) to attach it - and like you said - simple:

One remaining question on the re-plumbing. The plate heat exchanger "returns" to a half inch inlet on the top front corner of the boiler, while my new "S plan" layout returns to the old/existing CH 22mm return (via the pipework for the new system by-pass valve) on the side of the boiler. A simple cap nut on the redundant top half inch inlet would stop it leaking, but would it be better to cap it with a bleed valve as the plate heat exchanger pipework included one at that point (I can provide a picture if my words are unclear)?

View media item 42130

 

[oilhead]

If taking out the H/E. then there will be no need for the air vent.

 

[casparcat]

If taking out the H/E. then there will be no need for the air vent.

Thanks

 

[casparcat]

Might still need my crayons - while (still have just noticed that the Potterton System wiring diagram has an arithmetical error - the diagram clearly shows the zone valves feeding into a 7-terminal junction strip, while, on the same diagram (bottom right) the boiler terminal socket to which it refers is there clearly shown as a 6-terminal junction plug (as is actually fitted to my boiler).

As 7 into 6 does not go, it looks as if (counting from the top) the 6 terminal block is actually [1/6:HW-ON][2/6:L][3/6:S/L PumpL1][4/6:X][5/6:N][6/6:CH-ON].

While the "boiler's" top 3 of 6 correspond with the "diagram's" top 3 of 7 and the location of N at 6/7 is clear, it's the use of all three terminals of the "room stat" on 5/7, 6/7 & 7/7 that seems to throw the "diagram's" Zone Valve wiring out.

I would have expected the Room Stat to be 1=CH-ON 2=C and 3=(not used-cooling?).

On that basis, presumably it's the inclusion of 5/7 in the Potter diagram that is spurious for CH-ON/RoomStat1 - which should really be routed to 4/6, where it will go via WHITE>PINK back to [S/L CH-ON], then it gives 3/6 for ORANGE [S/L Pump L1].
View media item 42217 View media item 42129

 

[oilhead]

The seven strip junction box is external. Your boiler terminal is the six strip on the left of you diagram where you will use only 4.

 

[casparcat]

For the benefit of posterity (that is anyone else trying to extend the life of a Stateman Flowsure Boiler but without the ineffective plate heat exchanger) my efforts are now up and running.

With the S-Plan plumbing complete (CH Zone Valve, DHW Zone Valve and to replace the original Diverter and a by-pass valve added) the DHW was connected up to a new Thermal Store tank that included a Tank Stat and a HW circulation pump.

This left the re-wiring of the Flowsure into the new S-Plan controls (by-passing the old electro-mech clock and taking out both Diverter and Flow Switch circuits).

After a fair amount of use of the old test kit and crayons, I finally worked out what influence the relay was having on the Flowsure's internal wiring, which enabled me to work out how to link in the S-Plan and Thermal Store wiring effectively.

As wired, the DHW circulation pump only runs when the Thermal Store is up to temperature (hopefully from solar thermal heat - interlinked thermostats not shown on diagram) and the boiler only runs DHW "top-up" when solar thermal input not available.

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