Is this normal for a Y plan

[gash2024]

Ive just had my system changed over to a y plan and although iam more than happy with the results iam just unsure of one thing.
If both the HW and CH are switched on the pump runs continuously, if i have the HW running the pump runs continuously but if i only have CH or the cylinder stat stops calling then the pump only works when the boiler ( myson economist) fires up and then stops again when the boiler stat kicks in.
The sparky asked me to give it a good run and see how things go and if there were any problems he would come back but i dont want to waste his time if everything is working as it should.

 

[Agile]

What you have written seems a little muddled. However, I dont think its right. I am wondering why you had it wored by an electrician rather than a heating engineer.

The pump should run until the room stat is satisfied on CH.

The pump should run until the cylinder stat is satisfied on HW.

Tony Glazier

 

[gash2024]

The plumber we use said he couldnt wire it up, he gave no reason but it was a pain even for the electrician because of the way it had been wired up to run with just a 2 way valve of one pipe.
I will try and explain it more clearly.

1. If i choose HW and CH the boiler fires up and when the boiler switches off between heating cycles the pump continues to run until the next heating cycle and for the length of time i have the system turned on.

2. If i choose HW the pump acts in the same way in that it always is running but if i turn the cylinder stat right down the pump stops working and the boiler stops.

3. If i just choose CH the rads get hot and the pump and boiler work but when the boiler ends a heating cycle the pump stops working aswell instead of continuing to run until the next cycle or until i switch the system off.

I think number 1 and 2 scenarios are correct but iam concerned that number 3 isnt correct and the pump should continue to run until A i switch the system off or B the room stat stops calling for heat.

 

[Agile]

No. 3 is wrong.

But you have not told us your boiler make and model. That could make a difference just possibly in a month of Sundays.

Its difficult for me to imagine exactly what he has wired wrong but wrong it is!

Tony

 

[Gas2Air]

I suspect your system was upgraded from a gravity HW pumped CH system. This being the pump now runs on HW demand, the motorised valve opens on CH demand and delivers heating. If both are demnading heat then the pump will run, if CH is satisfied pump will shut off if HW also satisfied.

 

[gash2024]

The boiler is a myson economist.
It is pumped CH and HW like it was before its just before it only had a 2 way valve on the CH pipe so we were always heating the water.

Thing is the pump works continuously if iam heating the water but the boiler doesnt work continuously it comes on for a bit then goes off for a bit which depends on what number i have it set at which i think is normal.
But when iam running the Ch the pump stops when the boiler shuts off then comes back on when the boiler kicks in which doesnt seem right because the HW doesnt work like that.
The room stat has a digital display and it could be showing 18 c and i have it set to 20 c so i know its calling for heat.

 

[Gas2Air]

I understand that, read what i said. Your valve only opened on CH demand, your pump an boiler were fed from timer on HW demand, changing that to Y plan needs more wiring to clock, cyl stat and new valve to work correctly.

 

[gash2024]

I as just pointing out it wasnt gravity fed and that they were both pumped before
The timer had to be changed and has been moved to the airing cupboard which is home to the cylinder and pump, it had to be done like this because i didnt want any extra wiring putting in through the house because it would have made a right mess.
The mains supply is still from a switch in the kitchen next to the boiler but some dope had run it through the room stat before entering the airing cupboard so the electrician would have had to rip up my nice new flooring and chop the wall out just to take a wire back down to the room stat if i hadnt rushed out at the last minute and bought a wireless stat.
A junction box has been installed in the airing cupboard and the additional wiring has been installed.

 

[gas4you]

This is going to be a wiring fault. It sounds like none of your 'tradesmen' have a clue about ch wiring.

Does anyone know if the Myson Economist has a pump over run? I can't remember

 

[D_Hailsham]

Does anyone know if the Myson Economist has a pump over run? I can't remember

Some do, some don't - depends on the model.

gash2024 - which Economist do you have? Model or GC number.

1. If i choose HW and CH the boiler fires up and when the boiler switches off between heating cycles the pump continues to run until the next heating cycle and for the length of time i have the system turned on.

2. If i choose HW the pump acts in the same way in that it always is running but if i turn the cylinder stat right down the pump stops working and the boiler stops.

In a Y plan system, when HW or HW and CH have been selected at the programmer, the boiler is powered through the HW thermostat. The boiler cycling will be due to the boiler's own thermostat turning the boiler off. But if the HW water is not up to temp or the room temperature is below that set on the room stat, the system will still be asking for heat. So the pump will continue to run.

In HW only the pump should stop when the HW stat reaches temperature. With HW and CH should continue running until both are up to temperature.

3. If i just choose CH the rads get hot and the pump and boiler work but when the boiler ends a heating cycle the pump stops working as well instead of continuing to run until the next cycle or until i switch the system off.

... i am concerned that ... the pump should continue to run until A i switch the system off or B the room stat stops calling for heat.

You are correct in thinking that the pump should continue until the room stat is satisfied. However, it could just be coincidence that the pump goes of when the boiler shuts down.

I don' t know if it will be any help, but here is the wiring diagram of a Y-plan. You could use it to check the wiring of your system

NB if you have an Economist with Pump Overrun, the wiring will be slightly different - which is why the Model/GC number is important.

 

[gash2024]

Iam pretty sure the boiler doesnt have over-run as its very old.
Iam going to have a word with the electrician as iam not happy with it.
Thanks for the help i will post the results.