Will this work as fully-pumped?

[Manyanga]

We're wanting to go fully-pumped while doing other work in the bathroom. I'd be VERY REASSURED if you people who know could tell me whether the arrangement in the diagram will work, using a Grundfos twin pump ('Pump Plan').

We have a standard old-fashioned vented system with gravity HW (28mm) and pumped CH (22mm), ground floor 24KW wall-hung boiler, upstairs cylinder. Very little space for replumbing in the boiler cupboard.

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• Manyanga
• 28 Oct 2008
• 1

I understand the twin pump allows the vent to operate as it should - could easily be offset otherwise. Alternatives were to move existing CH pump onto combined return at the boiler; or to add a second pump on DHW return - but I don't understand the wiring needed.

Grundfos say you have to keep the pumps free of air. How would we do that?

 

[HarrogateGas]

No.......

 

[Manyanga]

Aaaargh. Please elaborate Harrogategas, before I just decide to move house.

 

[ChrisR]

YOU've shown 4 pipes coming off the pumps??

 

[Manyanga]

As I understood it, the Grundfos Twin has a 28mm inlet at the bottom and a 22mm at the top - basically just an open pipe passing between the two pumps. Literature states: 'The Pump Plan base casting has a 3/4" tapping which effectively is connected to the inlet port. It may be used for a drain cock, manual or automatic air vent. It may also be used as a connection for a combined open vent and cold feed.'

 

[Manyanga]

Grundfos call this the UPP 15-50 dual head and have a pdf on their website - 1222.pdf

Just seemed an alternative to motorised valves, plus the fact it comes with a wiring centre which I might understand.

 

[Deleted member 105431]

Grundfos call this the UPP 15-50 dual head and have a pdf on their website - 1222.pdf

Just seemed an alternative to motorised valves, plus the fact it comes with a wiring centre which I might understand.

nothing wrong with grundfos dual head system, I've found them very reliable. (and better pumps than wilo etc)

 

[ChrisR]

GOt a linK? Grundfos have the world's worst website!

 

[Manyanga]

Very agreed about website. There must be a simpler route, but try

http://www.grundfos.com/web/homeUK.nsf/Webopslag/DMAR-4GLLZH

Then Click 'Documentation and Downloads' (NOT just the Downlaods link at the end)

Then click on 'webcaps' to open the catalogue.

The click 'Literature'

Then click 'Heating'

Then click 'UP/UPS Series 100'

The five pdfs down the page is 'Pump Plan'.

They seem to be trying to hide it!

 

[jameshayes]

well any way you install it will work but sadly not correctly.
1. the basics.what boiler is bing attached to this system.makers instructions need to be adhered to.re combined cold feed arrangement.
2. with some basic plumbing you can fit a 3 port valve and single pump in airing cupboard,get a pre wired system,drayton or honeywell.
3.change cylinder return position to be as near to boiler as possile,your diagram will heat some rads when heating is off.
there is more but going to pub now.good luck.

 

[Manyanga]

Thanks JamesHayes, though no reason why you would be reading this by the time you get back from the pub. Boiler is a Potterton Profile 80E. Just looked at their pdf, and it shows combined vent and feed on the open-vented fully-pumped plan. At present the vent and feed are separate, with the feed joining the 28mm HW return at the cylinder. Could be left like that - which, if either, is better?

Would it be better to go for a Y plan or S plan? I realise that would be more usual, just that I can get the Grundfos dual head cheaply. Also have read here and elsewhere that valves sometimes play up......

What do you mean about 'change cylinder return..' Sorry to be thick. The flow and return run pretty much side by side in real life, though my diagram doesn't show it!

Can I use check-valves to stop heat leaking out from HW circuit into CH circuit?

NB I'm not planning to do this myself, but I have to know what I am letting myself in for. I don't know any heating engineers, so I have to be able to discuss the system with whoever comes to give us a quote. One of our friends ended up spending a fortune on a Combi which turned out not to be what she needed.

 

[ChrisR]

I wonder if this will work!:
http://net.grundfos.com/Appl/WebCAP...U&typecode=S100FAM&appcode=HEATING&pdfid=1222

I see no reason why you shouldn't do any of the options youo or anyone else has mentioned. Lots of ways to skin the cat...

 

[Manyanga]

Thanks Chris - bit quicker than my click throughs! Takes you straight to the pdf page.

Not being pipe-and-pressure learned, I can't figure when combined vent and feed is better.... It would be easier to leave the connections as they are, with feed coming down to the HW return at cylinder, but I thought combining just behind pump was advised.....

There will only be 1.8 metre head above the pump, because the F&E is coming into the house from the attic.

 

[jameshayes]

pub full of morons so back here again.
the plot thickens so you have a profile 80e a fantastic boiler.
ok as it is on an existing gravity hot water system the following needs to be changed in and on the boiler.
figs from makers installation manual.well my one.
1.set change over switch on control box to fully pumped.fig2.
2.reposition overheat bulb. fig 21.
3.there should be a return injector disc in the return tee.fig 20b.remove this for better circulation if required.
read or advise your installer to follow the makers instructions.the section the system is important.
regard to cylinder return see fig6 diagram (ignore alternative bypass arangement) see where cylinder return is,yes closer to boiler.
only draw back is sometimes noise as 2 pumps are running and system needs to be clear of debris so not to jam non return valves.
going back to pub now,youth club should have been moved on now.

 

[Manyanga]

Thanks james. We should make sure the system is flushed as best it can be - valves will be new to it - as even the cylinder thermostat will be. It is a 1970s system that has remained without much control. (Though I have replaced the rads, so all but two are new.)