Correct Boiler Plumbing?

[Agile]

You are correct, its there Kevin.

But a couple of lines below it said that it was a "new house" which did not agree with such an old boiler and that non sequitur caused me to forget the precedent.

However, that does not alter my expectation of what the problem is likely to be that causes the slow HW heat up.

Tony

 

[ElectricEe]

Hi everyone,

Yes it is a two pumped system. Sorry about the 'new' house confusion, it's a 'new to me' house, bungalow actually but I'm in denial about living in a vertically challenged house

The boiler was installed on 10 August 2001 which makes it about 8 years old.

Interestingly I've found a name and number on the back of the Installation and Servicing manual - I'm pretty sure that I never want to see or hear from this guy though! Is there any way to see if he was Corgi registered 8 years ago? Not that I'll have any come-back all these years later, especially as the job was done for the little old lady that lived here before me and my family.

I mentioned a few posts that I didn't think the cyl stat was connected back to the controller. I have now proved it's not. When the controller is set to DHW, the cyl pump is powered but switched by the cyl stat. The boiler keeps giving heat then cuts out when it gets too hot.

If doitall is out there I'd be interested in his opinion and maybe even a quote.

 

[kevindgas]

the correct way to wire the cylinder circuit / pump is

timer h/w on to cylinder stat common
cylinder stat calling to h/w zone valve brown and h/w pump live
a permanent live to zone valve grey
zone valve orange to boiler

this is different to S plan because the pump must be with the valve and not the boiler to stop the C/H making the pump run

similarly the C/H circuit should be wired
timer to room stat
room stat calling to c/h zone valve brown and c/h pump live
a permanent live to zone valve grey
zone valve orange to boiler

 

[bengasman]

this is different to S plan because the pump must be with the valve and not the boiler to stop the C/H making the pump run

What is the advantage of altering the s-plan setup, am I missing the obvious?

 

[Norcon]

the correct way to wire the cylinder circuit / pump is

timer h/w on to cylinder stat common
cylinder stat calling to h/w zone valve brown and h/w pump live
a permanent live to zone valve grey
zone valve orange to boiler

this is different to S plan because the pump must be with the valve and not the boiler to stop the C/H making the pump run

similarly the C/H circuit should be wired
timer to room stat
room stat calling to c/h zone valve brown and c/h pump live
a permanent live to zone valve grey
zone valve orange to boiler

This won't work!
Draw it out and you will see why.

EDIT. Sorry my mistake. Just re-read the original post.
Two pumps!. Silly me.

 

[kevindgas]

this is different to S plan because the pump must be with the valve and not the boiler to stop the C/H making the pump run

What is the advantage of altering the s-plan setup, am I missing the obvious?

the missing link is 2 pumps

if you wire it up as an S Plan both pumps will run simultaniously
the only difference between S plan and S plan+ is the pump wiring needing to be with the motorised valve actuator (brown wire) rather than the switched live (orange wire)

 

[picasso]

showing my ignorance here , why would you need zone valves ? a check valve on both pumps would sort out any crossover of flow , then link in series the timer/stat/boiler on and pump , I think the op needs to get the connections at the boiler sorted before the system will function properly.

 

[bengasman]

What is the advantage of altering the s-plan setup, am I missing the obvious?

the missing link is 2 pumps

It seems I am the missing link today.

 

[kevindgas]

showing my ignorance here , why would you need zone valves ? a check valve on both pumps would sort out any crossover of flow , then link in series the timer/stat/boiler on and pump , I think the op needs to get the connections at the boiler sorted before the system will function properly.

to stop the power transfer between the 2 pumps

 

[Norcon]

the only difference between S plan and S plan+ is the pump wiring needing to be with the motorised valve actuator (brown wire) rather than the switched live (orange wire)

Is this Honeywells S plan+ you are referring too because I don't think its wired this way.

 

[picasso]

kevin could you explain "power transfer betwen pumps" thanks

 

[Norcon]

Two pumps will be energised Picasso ,which you may not want.
Relays would be needed.

 

[kevindgas]

picasso
the break between the grey and orange wires in each valve when deenergised (microswitch open) stops the H/W pump getting power from the C/H pump and vis-versa

if the pumps are wired to the orange both pumps will run when demand is needed from one circuit only

norcon
the S- Plan+ drawings i have are not honeywell but came from BG when i was with them i think they came from a book originally and were enlarged to A4 which is how i have them.

 

[DP]

Op might have a valid point when when he says pipe connections are wrong at the boiler as seen in figure 3.3

Has the cylinder been replaced or relocated?

Have fitted second pump to aid circulation in HW loop a few times, but the vent and feed need to be correct else pump over will take place.

 

[ElectricEe]

Op might have a valid point when when he says pipe connections are wrong at the boiler as seen in figure 3.3

Has the cylinder been replaced or relocated?

Have fitted second pump to aid circulation in HW loop a few times, but the vent and feed need to be correct else pump over will take place.

I don't know if the cylinder has been replaced but it's unlikely to have been relocated, as far as I can tell it's the most logical place to fit it. That said, logic doesn't seem to have come into play for this installation

Talking of vent and feed, there is no feed to the HW loop, just a single 22mm feed into the hot flow of the CH loop. The vent pipe is just a tee off the feed pipe in the roof space - is this normal?

I'm going to sketch what I know of the system tonight and will post this soon.

Thanks very much to all that have posted, although I'm still confused how to fix it. I'm thinking along the lines of changing the boiler end to Y Plan with a 3-way valve and have it single pumped - does that sound sensible?