Central Heating Identification!

[WelshJohn]

Hi everyone!

First post. I have been lurking for a little while, I have just moved into my first home and have found some really useful posts here.

I have delved into the Central heating system at my property. I was wondering if you could identify which type of plan I have from a few photos.

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• WelshJohn
• 23 Feb 2015
• 1

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• WelshJohn
• 23 Feb 2015
• 1

It looks like a Y plan without the Y! Downstairs there is a thermostat and a programmer. The programmer is an old switchmaster 900 and the thermostat was a sun vic 2259 before I swapped it out for a nest today.

The nest is up and running and working as expected. But the issue now is with the water. I have to leave the heating constantly on (nest has control), but turning the water off on the programmer seems to have no effect. I hear a humming from the pump and the boiler seems to fire every other minute or so.

Does my current CH plan stop me from having just the Central heating on? Is it some sort of timer system? And what's the best remedy to gain control of the water, without turning the CH off at the programmer?

Thanks, I also uploaded a picture of what looks like the water tank thermostat switch being off on the wall. You can see the White cable trailing in the second picture. Should I turn this on??

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• WelshJohn
• 23 Feb 2015
• 1

Thanks so much for your help.

Edit: To add some more information, I just timed the boiler bursts, their almost exactly 1 minute 30 apart. I have purchased a new Drayton LP112 that I am going to have fitted, but I'm not sure if the control of the HW is down to the programmer or the CH plan itself.

 

[ScottishGasMan]

Looking at your pictures you have an old fully pumped system with a zone valve for heating but not hot water.

This means you can run HW on its own, and when you want heating the valve opens to allow hot water to the radiators, but there will always be a loop of hot water being pumped to the hot water cylinder whenever you have the heating on.

The only way to gain control over this is to convert to an S or Y plan system. You could get a zone valve fitted to the flow to the cylinder making it an s-plan, the issue would be with getting the wiring to it from your controller /timeclock/nest. And Ideally you would then fit a bypass valve, but if there are radiators with no TRVs and the pump is wired directly to the zone valves as opposed to a boiler with overrun capabilitys then theres no need to have the bypass.

I would say if you take this option, run a cable with a few extra cores or an extra cable to the cylinder cubpoard and fit an automatic bypass, and this will save work if you get the gas boiler replaced in future as it will be ready to accept pump overrun and have correct bypass fitted.

Also when fitting another zone valve, you would buy a cylinder stat that would turn the HW off once the cylinder has reached a set temperature regardless of what the timer asks for to save money and getting scalding Hot water.

 

[Madrab]

Yup, ditto what SGM has said.

It's almost as if they wanted a W plan (hot water priority) without the diverter valve.

You wouldn't be able to control the HW with that setup unless you pop in the 2 port valve into the HW circuit and add a cylinder stat and again as SGM mentioned, checking if the boiler needs a bypass as you haven't said what's the make and model of boiler.

That cable from the fused unit, does it lead to the immersion heater that's poking out of the top of the cylinder (round black cap)? If so, that's there as a HW backup should the CH fail. Doesn't need to be on.

 

[WelshJohn]

Thank you both for your replies. What you have both said makes complete sense from how the programmer allows me to control the system.

At the moment I am leaving the HW on all day, so that I can have some sort of control of the CH. Given the current setup would it be easier to convert to an S or a Y Plan?

I'm not sure how costly leaving the HW on all day is going to be, I cant see a stat on the tank?

The boiler is I believe an Ideal Elan. Quite an old gas boiler, but it seems to be working well.

Yes, the fused cable is indeed leading to the black cap on top of the tank. I can leave this off with peace of mind knowing it is the immersion, and not affecting the operation of the CH.

 

[ScottishGasMan]

Yea, dont bother turning it on or the bills really will soar (if it still works lol)

Looking at the Pic, I would say s plan (as in one more 2 port zone valve, a cylinder stat and some cable) would be the easyest, and in my opinion the most straight forward wiring wise.

With regards to efficiency, then the Elan probably already heats up as much outside as it does inside under normal operation, so this wont save you millions but its a start, and can get you a more comfortable level of HW if it currently feels too warm.

From a DIY point of view its quite a job, as it will be an open vented system (small and big cold storage/header tanks in loft) of which the CH (smaller) one will need drain as will the heating system need drained below the level of the cylinder for you to cut into the pipe and fit the valve (in its self an easy job) as is the wiring if you take your time and draw out a wiring plan to make sure you got it right before you start.

However when you drain it you "MAY" struggle to refill it at its current age if there is sludge/restrictions in the cold feed pipework, it might be no prob at all but worth knowing before starting.