Converting C Plan to S Plan for Drayton Wiser install

[markptrueman]

As part of my plan to install a full drayton wiser system this summer, i'm looking to change my current C plan system into a fully pumped S plan as it seems to be a requirement of the wiser system.

I just wanted to check that my ideas below are correct.

My boiler is a Worcester Danesmoor 15/19 Oil fired boiler and from the installation manual it shows the following two setups for a basic gravity plan and Y plan.My system is exactly the same as the top diagram, but with a two way valve on the flow of the cylinder (and a cylinder/room stat).

Looking at these two diagrams it seems to me that it should be as simple as removing the cylinder from its current un-pumped feed (28mm) and return and plumbing it into the current central heating circuit (22mm) after the pump, replacing the 3 port valve in the second diagram with 2x2 ports, one on the heating side and one on the water side. Is this the correct approach? Is the reduction in pipe size an issue?

I'm also planning to move the current HW valve near to the boiler as it is currently next to the cylider in the airing cupboard and I have a lot more room in the cupboard where the boiler is situated.

Also, the boiler manual says there is no requirement for a system bypass, but is it still recommended to install one?

Is there anything else i should be aware of in doing this?

Thanks in advance for any pointers

Mark

 

[Terrywookfit]

Google Image Result for https://aimhome.files.wordpress.com/2013/01/s-plan-water-300x208.gif?w=300&h=208

 

[ericmark]

I am no plumber, and I also thought of leaving C Plan, and fitting a motorised valve, but my heating guy said the boiler cools by heating up the DHW, and so options were really only C or Y plan as even in Y plan default is DHW.

 

[max_lan]

I wouldn't. Ive had nothing but hassle with wiser.

TRVs that report a temperature to the phone app below the current set point. And yet the heating is not on.

TRV reading 2C different to the thermostat right next to it.

TRV reporting below the setpoint and the app says all heating is off, but it is on. Goes off for 30.seconds or so every 10.mins or so. Until I turn the bloody thing off.

The app doesn't show all the rooms. And doesn't show you when heating was on or off. "Comfort mode" supposed to learn how long it takes to heat up. Never learnt anything.

In the 6 months I've had it, 3 times had to contact customer support and they're pretty useless. Generally just turn it all off and on again. But when you wake up cold or cooked, it's pretty annoying.

 

[markptrueman]

I wouldn't. Ive had nothing but hassle with wiser.

TRVs that report a temperature to the phone app below the current set point. And yet the heating is not on.

TRV reading 2C different to the thermostat right next to it.

TRV reporting below the setpoint and the app says all heating is off, but it is on. Goes off for 30.seconds or so every 10.mins or so. Until I turn the bloody thing off.

The app doesn't show all the rooms. And doesn't show you when heating was on or off. "Comfort mode" supposed to learn how long it takes to heat up. Never learnt anything.

In the 6 months I've had it, 3 times had to contact customer support and they're pretty useless. Generally just turn it all off and on again. But when you wake up cold or cooked, it's pretty annoying.

Thanks for the review, however reviews are generally favourable (4-5*) so i've decided to go with it.

 

[woodpeckerx]

TRVs that report a temperature to the phone app below the current set point. And yet the heating is not on.

I've not found that at all, if the TRV in a room is below its set point it doesn't call for heat for that room.

TRV reading 2C different to the thermostat right next to it.

Perhaps gaining some understanding of how Wiser works might help, the TRVs attempt to estimate the temperature in the centre of the room using readings and an algo, its never going to be super accurate so you have to monitor your system and adjust the set points yourself to get the desired result. The thermostat in a room overides the TRVs readings in that room so if you want a more accurate temperature in some rooms add a thermostat to that room as well.

TRV reporting below the setpoint and the app says all heating is off, but it is on. Goes off for 30.seconds or so every 10.mins or so. Until I turn the bloody thing off.

If it comes on then one of the TRVs or theromstats is calling for heat, if what you see in the app isn't correct then you probably don't have the rooms setup properly.

The app doesn't show all the rooms. And doesn't show you when heating was on or off. "Comfort mode" supposed to learn how long it takes to heat up. Never learnt anything.

You have to setup the rooms in the app, if you can't see them then you don't have it setup properly.

I've never used comfort mode but the concept should work, its not rocket science. If you want the room to be a certain temperature at a certain time then you could always switch the system on earlier.

I'm replacing most of my heating system at the moment and finding it very good, so far I have 10 wiser TRVs and 2 thermostats, the rest where control is not so important are standard TRV4s and one rad with no thermostat so there is always one rad open.

 

[Madrab]

If this is the same boiler as yours (Danesmoor) then your boiler can be installed as a sealed fully pumped system or open vent fully pumped (Y or S plan).

Going to a S Plan with autobypass and Expansion Vessel and filling loop would be straightforward. Or retain it as an open vent and use the HW side as the feed and expansion but if an S Plan (or Y plan with all TRV's) then and Autobypass would still be needed.

 

[markptrueman]

If this is the same boiler as yours (Danesmoor) then your boiler can be installed as a sealed fully pumped system or open vent fully pumped (Y or S plan).

Going to a S Plan with autobypass and Expansion Vessel and filling loop would be straightforward. Or retain it as an open vent and use the HW side as the feed and expansion but if an S Plan (or Y plan with all TRV's) then and Autobypass would still be needed.

Thanks, i've decided to go with open vent Y plan, all TRVs apart from bathroom radiator. Also, as you say, the current HW side is converted to just the feed and expansion and the current heating side just gets plumbed into the HW coil on the "resting" side of the mid position valve.

 

[fixitflav]

Thanks for the review, however reviews are generally favourable (4-5*) so i've decided to go with it.

Why go for S-plan? If now or in the future you want to add weather compensation, priority HW (PDHW) is needed, and (unless the Wiser system can take care of it) S-plan needs a programmer with volt-free contacts, or an extra relay. And Y-plan has to be set up to give PDHW. If you go for W-plan (with either/or diverter valve) you get PDHW by default, wiring simpler and valve probably cheaper.

 

[markptrueman]

Why go for S-plan? If now or in the future you want to add weather compensation, priority HW (PDHW) is needed, and (unless the Wiser system can take care of it) S-plan needs a programmer with volt-free contacts, or an extra relay. And Y-plan has to be set up to give PDHW. If you go for W-plan (with either/or diverter valve) you get PDHW by default, wiring simpler and valve probably cheaper.

To be honest, i have chosen S/Y plan primarily because thats what most people seem to talk about. Thanks for mentioning this, i'll have a look into it.

 

[fixitflav]

thats what most people seem to talk about

I've always had W-plan and never found CH having to wait till the cylinder stat is satisfied to be a problem, even with 3 youngish kids. With weather compensation becoming fashionable it ought to be making a comeback

 

[markptrueman]

I've always had W-plan and never found CH having to wait till the cylinder stat is satisfied to be a problem, even with 3 youngish kids. With weather compensation becoming fashionable it ought to be making a comeback

In terms of weather compensation, im intending to hook the wiser system up to my Home Assistant installation from which i can interface with outdoor sensors, weather stations and forecasts so should be able to knock something up.

 

[fixitflav]

In terms of weather compensation, im intending to hook the wiser system up to my Home Assistant installation from which i can interface with outdoor sensors, weather stations and forecasts so should be able to knock something up.

I don't know, but I'd guess, that the Wiser can deal with PDHW - keep CH off while HW is called, and use higher boiler flow temperature. But the Y-plan valve then doesn't use its full functionality (and has more to go wrong). In the case of S-plan, there's also the wiring to the microswitches, avoided with W-plan.

 

[Madrab]

I guess you need to understand what you personal requirements are as far as what system you incorporate. Do you use a lot of hot water and have a new fast recovery HW cylinder? If so then PDHW (W plan) may be an option, if not then your CH may be impacted by the time it take the cylinder to recover.
Each has it's plusses and minuses. W plan with weath comp is becoming more popular given the way it can handle the different temp requirements that the CH may have coupled with the new fast recover cylinders. It really comes down to what you need it to do and what you use.

Each has it's own benefits though Y play is actually the lesser of the 3 options these days as it has a tendency to burn out the motors due to the way the motor works when each is calling. IMO S(plus) plan wiring isn't that much more of a headache TBH and its all handled via a centralised wiring centre anyway, as any of the systems, practicality wise, would need to be.