Y Plan - 2 pumps

[RobW5]

The bungalow I've recently moved into had to have the heating on to get hot water, the indirect hot water cylinder was in parallel with the central heating with a wax thermostat to shut it off when it reached temperature.

This was inconvenient and frankly useless.

Today I added a V4073A mid position valve, Honeywell ST9400C programmer, Danfoss Programmable room stat and a Honeywell tank stat.

Used a Honeywell wiring centre and it all works perfectly, just hot water, heating or both. I'm quite chuffed as I've never done any plumbing before. Electrically qualified so the control wasn't a problem.

While wiring I found a 2nd pump I never new existed.

So my question is, as this pump is downstream of the mid position valve it will be trying to pump nothing when it's on hot water only.

Will this cause problems?

If so can I use the Room stat output to control the 2nd pump so that it only runs when the heating is on? This will only be live when heating is called and the stat is closed?

I can't see why not, just wanted to ask first and see if anyone could tell me how 2 pumps are normally controlled with a Y Plan setup.

Thanks for any advice.

Rob.

 

[45yearsagasman]

On a correctly configured Y Plan a 2nd pump is not required. It would be best removed and a piece of pipe used to fit gap. I assume that it's downstream on the heating circuit.

 

[ALCPlumbing]

If you're going to wire second pump in come off the orange from the 3 port valve. This means it will only pump when heating is called for and valve has opened fully to the heating circuit.

 

[ALCPlumbing]

But as 45yeargasman said you won't need it so just cut it out.

 

[RobW5]

If you're going to wire second pump in come off the orange from the 3 port valve. This means it will only pump when heating is called for and valve has opened fully to the heating circuit.

Wouldn't orange be live whenever the boiler is on, hot water or heating?

From Honeywell:- Valve wiring configuration is:
White = Heating on
Blue = Neutral
Grey = Hot water off
Green/Yellow = Earth
Orange = Boiler and pump live.

So did you mean white, which is where I'll try connecting it. (Output of room stat)

Yes the pump is downstream on the heating circuit. Are you saying that a 2nd pump is NEVER required?

I have no problem removing it but as all the radiators work well I'd rather leave it unless it can cause problems I'm not aware of.

Cheers,

Rob.

 

[stardanny]

Best not wired up 2nd pump if the heating working ok.

Really, it should be removed, remove pump, pump valves and fit 2 straight compression joints with piece of pipe.

Daniel.