S-plan plus question

[19KD75]

Hi, I am planning an all-new central heating and hot water system in my house renovation. The house is a Victorian detached two bed, one bath, with 9in brick walls, 500mm of loft insulation and retro-fitted double glazing in the original wooden sash frames.

I have bought, or intend to buy the best parts I can for my system. I plan on fitting a Vaillant or Worcester Bosch condensing combi - I can't decide which to go with - with Stalrad radiators, Pegler Bulldog TRVs, and Honeywell controls. With the heating, I'd like to fit the system as S-plan plus, I have a couple of questions I thought you learned people might help me with?

Will I need to fit two programmable (as opposed to standard room) thermostats for the system to run at optimum? I intended on using the CM907 7-day unit.

This is my first foray into heating systems, but I hope that with some guidance, I can make it a good one!

 

[mysteryman]

As you are starting from scratch - do the job properly and fit a quality boiler with built-in weather compensation.

 

[kevindgas]

personally i would go with a horstmann H37 timer then 2x room stat & 1x cyl stat
bulldog TRV's are ok but you could get a better deal off city plumbing the IFLO trv's are cheaper and of a similar quality
buy a 2 zone controls pack and then the additional bits you need

 

[D_Hailsham]

I'd like to fit the system as S-plan plus.

Do you want separate time and temperature control in both heating zones, or time and temp in one zone and temp only in the second zone?

 

[19KD75]

Thanks for the replies so far

The weather compensator is a good idea, and has come up in my searches through system planning design It is available as an add-on to Honeywell controls.

I'd like both time and temp to be independant of each other - one zone will be downstairs, one upstairs. I guess I could live with a 1-day program controlling the upstairs CH, with a 7-day running downstairs CH?

Does anyone have an opinion on the Fernox Boiler Buddy or the Magnaclean?

 

[kevindgas]

magnaleaks are out of vogue, due to seal issues we are fitting TF1's from fernox at the moment and they seem ok.
spirovent's are equally as good.

 

[evsy01]

If you are fitting a new system which you said you are as long as all the flux and debris out of the system and an inhibitor (sentinel x100) then a magnaclean is not required

 

[D_Hailsham]

The weather compensator is a good idea, and has come up in my searches through system planning design It is available as an add-on to Honeywell controls.

Where did you get the Honeywell info from? A link would be helpful.

If you want weather compensation, the boiler has to be designed to understand it; you can't just "add it on".

 

[19KD75]

Will see if I can find it

 

[19KD75]

Well, I was half right! The outdoor temperature sensor is for information only, not for use in weather compensator function....back to the drawing board.

I've plumbed (no pun intended) for the Vaillant ecotec 837. I'm not going for the Vaillant controls, though.

I want to use the Honeywell ST9400 or 9500 controller for my S-plan plus system, but will this cause problems with a combi? I'm guessing the two two-port (heating zone) valves will be able to figure out the demand from the controllers, won't they?

Still unsure about the thermostats for the system though, either Honeywell T6360 or CM907. Really can't decide on whether the 7 day programming is a necessity, but I am trying to make the system economic, reliable and 'future-proof', I guess, to a certain degree?

 

[D_Hailsham]

I've plumbed (no pun intended) for the Vaillant ecotec 837.

Unfortunately, the word you were thinking of is plumped.

Why such a large boiler for so small a house. It's heating output is 12-28KW and you will possibly need less than 12kW.

Check your heating requirement using the Boiler Size Calculator.

Have you measured the incoming cold water flow rate (at kitchen tap) to see if you need 37kW for heating the hot water?

I want to use the Honeywell ST9400 or 9500 controller for my S-plan plus system, but will this cause problems with a combi?

With a combi, you don't need time controls on the hot water, just the heating.

Why do you need two zones for heating in such a small house?

Still unsure about the thermostats for the system though, either Honeywell T6360 or CM907.

As well as being a programmable stat, the CM907 is also a digital stat, so it is more accurate than the T6360. The DT90E is better than the T6360 if all you want is a stat.