Adding a Grundfos Pump to Semi-Gravity system

[Newboy1996]

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.
Boiler has got 4 tappings, so it will have the 2 pumps when done.
I was going to put it in the flow pipe, leaving it on the lowest setting as not to over pump into the cistern!

What do you think?

 

[kevplumb]

depends where the cold feed / expansion is

 

[picasso]

this might help

http://www.pumptool.co.uk/Position.html

 

[Newboy1996]

this might help

http://www.pumptool.co.uk/Position.html[/QUOTE]

Its becoming headache now!
Can you get pumps that are not as powerful to use, reduce chance of water all over the place?
When I added the zone valve to the gravity side I did not think it would reduce circulation so much?

 

[bengasman]

...Can you get pumps that are not as powerful to use, reduce chance of water all over the place?

What do you mean?

When I added the zone valve to the gravity side I did not think it would reduce circulation so much?

It is not supposed to reduce it, it is supposed to shut it off completely.

 

[tamz]

If you are thinking of adding a pump to the gravity side of the system it should not be done. Why don't you just convert it to fully pumped S plan?

From this http://content.honeywell.com/uk/homes/Schemes/c.jpg

to this http://content.honeywell.com/uk/homes/Schemes/s.jpg

There are better drawing out there if you look.

Just an afterthought; the motorised valve you added should have been 28mm and if you have solid fuel (no S plan allowed) it should have been a 4043B normally open valve.[/img]

 

[Nige F]

...Can you get pumps that are not as powerful to use, reduce chance of water all over the place?

What do you mean?

When I added the zone valve to the gravity side I did not think it would reduce circulation so much?

It is not supposed to reduce it, it is supposed to shut it off completely.

Even open it creates a restriction that slows the gravity circuit . When I was a Newboy myself -20 years before 1996, I made the same mistake on a couple of rads...1/2 inch wont work on gravity . had to replace with specials made with 3/4 inch tappings

 

[bengasman]

True as that may be, I understood that the op wants to convert to fully pumped.
Bit hard to advice people that give info in shorthand.

 

[Newboy1996]

At the moment the CH side is very stable with no pumping over caused by its pump (remember 4 tapping on boiler).
If I add a new pump to the system on the DHW side, making it pumped with 2 port MV. This should still balance and not see-saw as CH pump will be off when new pump runs for DHW.
Then boiler + new pump will only get a live from an open MV near cylinder (leaving CH out of the picture of course, which could be inactive at the time).
CH and DHW pumps can run at same time though

 

[Terrywookfit]

You will need a relay, so that the boiler can operate with either or both pumps.
Ideally the vent should be taken directly from the boiler with an aav on primary flow.

 

[Newboy1996]

You will need a relay, so that the boiler can operate with either or both pumps.
Ideally the vent should be taken directly from the boiler with an aav on primary flow.

The vent is close coupled near cylinder, for the reason a one hell of a trip down to the boiler pipe route!
I am thinking of adding the other 2 port valve instead of pump to increase water flow through DHW side. At the moment most water is just wanting to migrate into the rads past the CH pump!

 

[Tipper]

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

First I added a cylinder thermostat and 2-port valve located down close to the boiler return.

Some years later (10ish) I added a circulating pump between the valve and the boiler to improve HW recovery time following the addition of 2 power showers to the bathrooms. It worked perfectly!

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.

Adding a second pump was far cheaper, and more importantly, less disruptive than replumbing the system into a more contemporary set up.

 

[Newboy1996]

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

First I added a cylinder thermostat and 2-port valve located down close to the boiler return.

Some years later (10ish) I added a circulating pump between the valve and the boiler to improve HW recovery time following the addition of 2 power showers to the bathrooms. It worked perfectly!

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.

Adding a second pump was far cheaper, and more importantly, less disruptive than replumbing the system into a more contemporary set up.

Where you blessed with F&E pipes exactly in the right place, just beside the boiler?? Did you pump into the boiler or out from it?
How high was the feed tank from the boiler?

 

[Tipper]

F&E were upstairs by the HW cylinder, both new pump and valve added to the boiler return at the boiler so pumping into the boiler, feed tank in the loft so about 15' above the boiler.

Because replumbing would have meant lifting carpets and floorboards to run in new F&E pipes down to the boiler and making a god awful mess, I went for a pumped return as a simple but not necessarily 'approved' method. The CH was pumped return too 'cos that's how it was done about 30 years ago!

(IIRC all the regs say is thermostats and zone valves and anti-cycling of the boiler they don't prescribe how you achieve it!)

 

[Terrywookfit]

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.