C plan to S plan fully pumped

[bhm1712]

I think its about time i converted to fully pumped. In terms of pipework, is this something which im allowed to do myself? (No gas pipe work only water) and if so, how would be the best way to do it?

At the moment my boiler is in the garage with the flow and returns for primaries and secondaries coming straight out of the top of the boiler and into the celing (about 18 inches above the boiler). The motorised valve for the hot water is in the primary return and the CH pump is on the secondary return pipe.

So basically, how would you go about altering the pipework to be compatible with S plan? wiring wise its ok as i am an engineer and will notify. The reason im going for S plan over Y plan is because i have not got the option to pull in a new cable from the timer to the boiler and for Y plan i would need an extra wire for HW off.

 

[D_Hailsham]

A pic of the boiler etc, with everything labelled, would be very helpful.

 

[bhm1712]

thought somebody would ask for a piccy, i will get one ASAP.

 

[yodaveg]

S plans are better anyway, greater flow rate, easier to wire, easier to fault find. Don't forget you can get wireless room stats, cyl stats and programmers!

 

[bhm1712]

 

[D_Hailsham]

Thanks for the pic.

I assume you have confirmed, by visual inspection, that the pipes are as labelled.

The CH pipe look like 22mm and I assume the HW pipes are 28mm.

Where do the feed and vent pipes from the F/E tank join the system?

A fully pumped system only uses two connections - in your case they are the CH flow and HW return. The other two will need to be blanked off.

There will be quite a lot of pipework alteration. I only hope there is enough room above the boiler to accommodate it.

You may have to put a one-way valve in the CH return to prevent reverse flow when on HW is ON.

Untitled

• D_Hailsham
• 4 Dec 2011
• 1

 

[bhm1712]

please excuse the poor effort on paint, but here is how the pipework is at the moment.

Yes the pipes are verified as being how they are labelled in the first picture. The HW pipes are 22mm as well - wrong i know!! thats why i struggled to get a 22mm 6 wire motorised valve for the c-plan. Couldnt find a honeywell one. Eventually found the Salus website!

 

[bhm1712]

i think the main issue here will be getting the feed and vent pipes re plumbed, as they currently terminate at a T with the cylinder coil in the airing cupboard. They will need to go into the garage, unless it would be possible to leave them on the return pipe as i have seen on other pipework layout diagrams?

http://www.miketheboilerman.com/pipeworklayouts.htm

second picture

 

[Hugh Jaleak]

I dont know the logistics of your property but when I converted mine from gravity HW/pumped CH to fully pumped I used the existing 28mm primaries from boiler to airing cupboard as flow/return from boiler. New boiler was relocated to utility room, 22mm pipes run back to kitchen to join existing 28mm's.

I picked up from the other ends of the 28mm flow at airing cupboard, into 22mm, using 'H' arrangement for vent/cold feed, then relocated pump, and fitted 3 way valve. Ran 22mm flow/return from airing cupboard back to feed rads. (Must common returns from Rad's before returning to boiler.)

 

[bhm1712]

im not upgrading the boiler, just making it fully pumped. Cant justify a new boiler as im not planning on staying here longer than 2/3 years more. I couldnt do what you have suggested.

 

[bhm1712]

would this layout work and be safe? this is my interpretation of the second picture on that miketheboilermans website for use with my system.

 

[Hugh Jaleak]

I appreciate you want to keep the boiler, if I had kept my old Potterton Kingfisher i'd have capped the CH flow and return at boiler.

The layout in your picture wouldnt be safe as you have the motorised valve before the vent. Vent needs to be a completely unobstructed path from the boiler to over the F&E tank. Valve must be after the open vent.

 

[bhm1712]

but it is not obstructed through the return pipe, would the water not expand through that way if there was an overtemp or high pressure?

im not trying to be awkward, im just trying to understand. I only thought it would be ok that way due to the second system shown on the website i posted a link to, which the guy says is an actual system?

Of course, im trying to do it the simplest way at the same time, without compromising safety. If the pipes have to be as shown in D_Hallishams sketch thats fine...i will have to do it that way.

Here is the system im speaking about. the website text says 'System layout diagram reproduced from the Keston Celsius 25 installation instruction manual.':

 

[yodaveg]

would this layout work and be safe? this is my interpretation of the second picture on that miketheboilermans website for use with my system.

If you move the M valves on to the return pipes this would work as the boiler still has an unrestricted passage from flow to vent. If M valves ever failed the pump would push water into F and E tank at quite a rate. Might be worth upgrading overflow to larger diameter. With this arrangement you could join both returns after the m. valves then connect back to the boiler. Then split the flow pipe below the cieling to feed cylinder and rads. Or fit another pump and keep all pipes?

If it were me I would pressurise the system and get rid of the the tank, vent and feed pipe work.

 

[bhm1712]

would that be allowed then? fitting the MV in the returns on an S plan?

wouldnt the water be pumped into the F&E tank at a fair rate if the valves were fitted either way (in the flow or return) ? surely it would, and thats the point isnt it?

If i kept both sets of pipes, it wouldnt be compliant as far as im told..modern boilers dont come with twin tappings so if it failed i would be back to square one with altering pipework.