Adding a Grundfos Pump to Semi-Gravity system

[D_Hailsham]

I would be very interested to know how you got Independant time and temperature control of heating and hot water without using a relay.
How did you manage to independantly control two pumps with only one set of contacts in the zone valve?

The standard C plan wiring requires a spdt switch, ie the V4043H valve

View media item 73
The valve is normally closed, so no circulation through the cyclinder circuit. The heating pump is wired so it only comes on when the room stat calls for heat.

The hot water pump could easily be wired so it only comes on when the cylinder stat closes, i.e connected to terminal 8.

CH only: CH pump runs via terminals 5 and 9
HW only HW pump runs via terminal 8

The design of a C-plan does not allow both pumps to run at the same time.

 

[Terrywookfit]

I would be very interested to know how you got Independant time and temperature control of heating and hot water without using a relay.
How did you manage to independantly control two pumps with only one set of contacts in the zone valve?

The standard C plan wiring requires a spdt switch, ie the V4043H valve

View media item 73
The valve is normally closed, so no circulation through the cyclinder circuit. The heating pump is wired so it only comes on when the room stat calls for heat.

The hot water pump could easily be wired so it only comes on when the cylinder stat closes, i.e connected to terminal 8.

CH only: CH pump runs via terminals 5 and 9
HW only HW pump runs via terminal 8

The design of a C-plan does not allow both pumps to run at the same time.

I know how a C plan works

He is using TWO PUMPS!

A "C" plan is gravity!

You did not read what I wrote

The easiest way is to use a DPDT relay.

 

[D_Hailsham]

I just want to check about the position of a circulator I am adding to a semi-gravity plan. I have already added a 2-channel programmer, 2 port zone valve to get independant control.

I assume that the zone valve is in the HW circuit, so he has already converted to C Plan and just wants to add a pump to the HW circuit. This can be done in the way I suggested.

I am surprised that you did not pick up the error when I said you can't have HW and CH running at the same time. Both pumps will run and the boiler will be ignited via the grey and orange wires.

 

[bhm1712]

my motorised valve didnt appear to slow down the flow at all on my gravity circuit.... what type is yours?

 

[Newboy1996]

my motorised valve didnt appear to slow down the flow at all on my gravity circuit.... what type is yours?

The previous plumber saved a bit of cash by only plumbing to the boiler with 22mm, leaving top section still 28mm. I think this is the bad circulation problem. Horstmann valve.

 

[Newboy1996]

I updated my gravity HW exactly as you want to do.



And you don't need a relay. I used the auxiliary switch on the valve plus a bit of a rethink on the wiring logic.

Sorry haven't got a copy of the wiring diagram I drew up as I sold the house 2 years ago and the information file on the boiler, etc, all went with it.

I would be very interested to know how you got Independant time and temperature control of heating and hot water without using a relay.
How did you manage to independantly control two pumps with only one set of contacts in the zone valve?
Two sets are needed. D/P c/o.

One zone valve (at the moment) does two jobs. Orange from valve does HW and NEW pump. WHITE on MV does live for old CH pump (will be done off orange wire on NEW CH MV when fitted)

 

[D_Hailsham]

One zone valve (at the moment) does two jobs. Orange from valve does HW and NEW pump. WHITE on MV does live for old CH pump (will be done off orange wire on NEW CH MV when fitted)

If you have separate pumps in the CH and HW circuits, you do not need motorized valves as well. The pump acts as a valve when it is not turning.

Grundfos relied on this in the PumpPlan

 

[gassafeman]

Cant a 'C' plan work?

If you are hell bent on a fully pumped system, lift a few boards and convert to an 'S' plan.

Paul

 

[Tipper]

Oh come on guys!

All you see is what they told you at college.

Use your brains and work it out.

That's what I did and it WORKED!

(But sorry OP I don't have either the piping diagram or elec wiring diagram but there were 2 pumps, one valve and no relays.)

 

[bhm1712]

The OP is correct, its easy with a c plan. you do not need a relay, you just take a live from terminal ten which off the top of my head is for the orange wire for HW on. when the valve opens for HW and supplies the live via the orange wire to open the boiler gas valve, the pump will then turn on too, for HW. The central heating pump takes its live from a different terminal in the C plan which is independent from the HW live. so it can be done easily. Both pumps can run together or independently

 

[doitall]

The OP is correct, its easy with a c plan. you do not need a relay, you just take a live from terminal ten which off the top of my head is for the orange wire for HW on. when the valve opens for HW and supplies the live via the orange wire to open the boiler gas valve, the pump will then turn on too, for HW. The central heating pump takes its live from a different terminal in the C plan which is independent from the HW live. so it can be done easily. Both pumps can run together or independently

Isn't that what D Hailsham said yesterday

To the OP if he continues with the hair brained idea, the pump must be on the return, and depending on the boiler make and model, it may also require an injector tee or spreader tube.

And a C plan is for gravity primary circuit, as above sticking a second pump will most certainly cause boiler issues.

 

[JohnD]

I did my old mum's gravity HW not long ago. Put a 28mm motor valve and an extra pump on, plus a new wiring centre and changed the programmer wiring. The 2-port valve has a microswitch in it that turns the pump off. The 28mm valve has an extra wire that the 22mm valve doesn't, for that purpose

A few observations:

It speeded up the Cylinder heating time enormously, and cut down the summer gas usage by about half (the boiler is a big Potterton Profile with a lot of iron in it)

I insulated the HW circuit pipes with thick Climaflex as there are a lot of losses from those 28mm pipes in a long run (even though, with the cyl stat and 2-port valve, they are not hot all the time any more)

Pumping the HW circuit dislodged a lot of old sediment out of the pipes and cylinder (I had previously cleaned the system and added a Magnaclean, so I knew where the dirt had come from)

I chose to add the 2-port and extra pump because, due to building work after the boiler was installed, and there was an Upstairs and a Downstairs CH circuit, I was scared of having to reconfigure all the pipes in a constricted space to put in a 3-port valve. I had picked up a 28mm 2-port and a new pump at good prices (28mm valves are particularly expensive, especially the 3-port). I did it with the help of my BiL who is a refrigeration and air con engineer, and competent at pipework and wiring controls. I found the controls quite difficult to grasp and got lots of help on here.

I had fitted gate pump valves, and turned them down a lot as it tended to get slight unwanted circulation through the CH and would briefly pump over at start-up if CH was already running.

On consideration I suppose it would have been better to bite the bullet and fit a 3-port valve, though I would probably have had to pay a pro to do it

 

[D_Hailsham]

The OP is correct, its easy with a c plan. you do not need a relay, you just take a live from terminal ten which off the top of my head is for the orange wire for HW on. when the valve opens for HW and supplies the live via the orange wire to open the boiler gas valve, the pump will then turn on too, for HW. The central heating pump takes its live from a different terminal in the C plan which is independent from the HW live. so it can be done easily. Both pumps can run together or independently

Isn't that what D Hailsham said yesterday

No, it isn't what I said.

If you connect the HW pump to terminal 10, it will run whenever the boiler is on as this is the terminal which supplies power to the boiler. The HW pump must be connected to terminal 8.

The operation is then as follows:

CH only Room stat closes and supplies power to CH pump via terminals 5 and 9, which also supplies power via the white and orange wires to the boiler.

HW only HW stat closes and supplies power to HW pump connected to terminal 8, which also supples power to the valve motor. The valve opens and the switch moves over, connecting the grey wire (permanently live) to the orange wire, which lights the boiler.

HW and CH Room stat closes and supplies power to CH pump via terminal 5 and 9. HW stat closes and supplies power to HW pump connected to terminal 8, which also supples power to the valve motor. The valve opens and the switch moves over, connecting the grey wire (permanently live) to the orange wire, which lights the boiler.

 

[doitall]

I did my old mum's gravity HW not long ago. Put a 28mm motor valve and an extra pump on, plus a new wiring centre and changed the programmer wiring. The 2-port valve has a microswitch in it that turns the pump off. The 28mm valve has an extra wire that the 22mm valve doesn't, for that purpose

A few observations:

It speeded up the Cylinder heating time enormously, and cut down the summer gas usage by about half (the boiler is a big Potterton Profile with a lot of iron in it)

I insulated the HW circuit pipes with thick Climaflex as there are a lot of losses from those 28mm pipes in a long run (even though, with the cyl stat and 2-port valve, they are not hot all the time any more)

Pumping the HW circuit dislodged a lot of old sediment out of the pipes and cylinder (I had previously cleaned the system and added a Magnaclean, so I knew where the dirt had come from)

I chose to add the 2-port and extra pump because, due to building work after the boiler was installed, and there was an Upstairs and a Downstairs CH circuit, I was scared of having to reconfigure all the pipes in a constricted space to put in a 3-port valve. I had picked up a 28mm 2-port and a new pump at good prices (28mm valves are particularly expensive, especially the 3-port). I did it with the help of my BiL who is a refrigeration and air con engineer, and competent at pipework and wiring controls. I found the controls quite difficult to grasp and got lots of help on here.

I had fitted gate pump valves, and turned them down a lot as it tended to get slight unwanted circulation through the CH and would briefly pump over at start-up if CH was already running.

On consideration I suppose it would have been better to bite the bullet and fit a 3-port valve, though I would probably have had to pay a pro to do it

And what happens when something goes wrong John.

Is the open vent still unrestricted to atmosphere.

 

[JohnD]

yes

pump and valve are both on the HW return (adjacent)

HW flow has the vent teed off and going into the loft

(F&E is on a tee at the cyl coil and also goes into the loft