DIYnot
Local | Network
   DIYnot > Forums
Local | Network
DIYnot Network Local DIYnot Network Local  
  Forum IndexForum Index     RulesRules    HelpHelp     Join FREERegister Free     About CookiesCookies     SearchSearch     LoginLogin 

central heating pump max delivery head advice needed

Goto page 1, 2  Next
 
Post new topic   Reply to topic    DIYnot.com Forum Index > Plumbing and Central Heating
Search this topic :: View previous topic :: View next topic  
Author Message
ashneedham

from United Kingdom

Joined: 30 Jul 2013
Posts: 11
Location: Derbyshire,
United Kingdom

PostPosted: Tue Jul 30, 2013 6:21 am Reply with quote

Hi all,
I believe I am in need of a new central heating pump. My system is a traditional open vent (I think that's the right term?). Living in a 2 up 2 down, we have an old boiler in the kitchen and the pump is in the airing cupboard upstairs. We have fitted a new rad downstairs and came to test it. the system fired up ok but we got no heat in downstairs rads only up. We drained the whole system whilst installing the new rad and bled the rads before starting again. From what I have researched it sounds as if the pump has gone.

The pump is a Grundfos 15-50 and probably been in over 20 years. I have been looking at screwfix and there is a Wilo that has good reviews and sounds like a good replacement. But it states that the Max Delivery Head is only 4m. Is the delivery head that total distance that the water needs to flow vertically?

My rooms are about 2.5m tall so from the highest pipe to the lowest is a out 3m. But I think that the pipes are setup so that the water returns back upstairs to the airing cupboard before going back to the boiler. Would that mean I have to get a max delivery head of about 6m? (Because effectively the water is flowing uphill twice, once from the boiler and again before returning to it).

I know people will suggest to get the best I can afford but at the moment I really can't afford much over 60 and I am reluctant to spend too much because I plan to replace the central heating next year and so the pump may not be needed.

Any advice or help is appriciated

Thanks
Ash
Back to top
 Alert Moderators

If you do not want to see this advert, click here to login or if you are new click here to join free.
D_Hailsham

from United Kingdom

Joined: 18 Oct 2007
Posts: 8713
Location: Sussex,
United Kingdom
Thanked: 1002 times

PostPosted: Tue Jul 30, 2013 8:46 am Reply with quote

ashneedham wrote:
We have fitted a new rad downstairs and came to test it. the system fired up ok but we got no heat in downstairs rads only up. ... From what I have researched it sounds as if the pump has gone.

Don't jump to conclusions; it's very unlikely that the pump has suddenly given up just when you fitted a new radiator.

Is the new rad a replacement or an addition?
Did you have the system turned off when bleeding the rads?
Was the motorised valve set to open when bleeding?
Did you bleed the downstairs first?
Did you bleed the pump?
Did you balance the rads after fitting the new one?
Which speed is the pump set to (switch on the side)?

Quote:
The pump is a Grundfos 15-50. ... There is a Wilo ...it states that the Max Delivery Head is only 4m. Is the delivery head that total distance that the water needs to flow vertically?

No! The head is the pressure loss in the pipes that the pump can overcome. Nothing to do with height. Your Grundfos has a 5 metre head (that's the 50), so you would need one with the same head.
Back to top
 Alert Moderators
Agile

from United Kingdom

Joined: 26 Jun 2004
Posts: 52973
Location: London,
United Kingdom
Thanked: 3343 times

PostPosted: Tue Jul 30, 2013 9:48 am Reply with quote

I can see no reason to replace the pump.

But I do expect the system needs balancing.

Most would say that a Grundfos pump is worth the little extra if it needed replacement ( which it does not! )

Tony
Back to top
 Alert Moderators
CBF

from United Kingdom

Joined: 14 Oct 2012
Posts: 2165
Location: Hampshire,
United Kingdom
Thanked: 362 times

PostPosted: Tue Jul 30, 2013 10:05 am Reply with quote

It's most likely an air lock, turn off all the rads upstairs & turn off the hot water on the programmer (if you can) if all the downstairs rads don't get hot then turn off the ones that do & that should force it round the others, if both ends of the upstairs rads are fully open you need to balance the system, try turning the locksheild rad valves (upstairs) so it's only open 1 1/2 turns that's a good starting point


Last edited by CBF on Tue Jul 30, 2013 10:07 am, edited 1 time in total
Back to top
 Alert Moderators
ashneedham

from United Kingdom

Joined: 30 Jul 2013
Posts: 11
Location: Derbyshire,
United Kingdom

PostPosted: Tue Jul 30, 2013 10:06 am Reply with quote

D_Hailsham wrote:
ashneedham wrote:
We have fitted a new rad downstairs and came to test it. the system fired up ok but we got no heat in downstairs rads only up. ... From what I have researched it sounds as if the pump has gone.

Don't jump to conclusions; it's very unlikely that the pump has suddenly given up just when you fitted a new radiator.

Is the new rad a replacement or an addition?
Did you have the system turned off when bleeding the rads?
Was the motorised valve set to open when bleeding?
Did you bleed the downstairs first?
Did you bleed the pump?
Did you balance the rads after fitting the new one?
Which speed is the pump set to (switch on the side)?

Quote:
The pump is a Grundfos 15-50. ... There is a Wilo ...it states that the Max Delivery Head is only 4m. Is the delivery head that total distance that the water needs to flow vertically?

No! The head is the pressure loss in the pipes that the pump can overcome. Nothing to do with height. Your Grundfos has a 5 metre head (that's the 50), so you would need one with the same head.


Hi D_Hailsham,
Thanks for the reply

The radiator is a replacement but bigger and on the other side of the living room so we extended the pipes.

System was off when bleeding.

Don't know what the motorised valve is?

Pump is set to speed 3. It has always been the same since we moved into the house.

Regards
Ash
Back to top
 Alert Moderators
Agile

from United Kingdom

Joined: 26 Jun 2004
Posts: 52973
Location: London,
United Kingdom
Thanked: 3343 times

PostPosted: Tue Jul 30, 2013 10:29 am Reply with quote

Regardless, it will still need balancing.

The pump should be able to give adequate flow on setting "2".

Tony
Back to top
 Alert Moderators
D_Hailsham

from United Kingdom

Joined: 18 Oct 2007
Posts: 8713
Location: Sussex,
United Kingdom
Thanked: 1002 times

PostPosted: Tue Jul 30, 2013 1:19 pm Reply with quote

ashneedham wrote:
Don't know what the motorised valve is?

There are two types - see pics:

Login to view this image Login to view this image

There will be one (left pic) or two (right pic), probably near the pump.

You open the valve by moving the lever in the slot to the MAN end. It then locks by catching in the "nick" or pushing in/out, depending on make of valve
Back to top
 Alert Moderators
steelmasons

from United Kingdom

Joined: 10 Oct 2011
Posts: 6649
Location: United Kingdom
Thanked: 1835 times

PostPosted: Tue Jul 30, 2013 2:41 pm Reply with quote

Agile wrote:


The pump should be able to give adequate flow on setting "2".



Stop jumping to conclusions.
Back to top
The following user says thank you to steelmasons for this useful post:
hazetimesfive (2 Aug 2013)
 Alert Moderators
ashneedham

from United Kingdom

Joined: 30 Jul 2013
Posts: 11
Location: Derbyshire,
United Kingdom

PostPosted: Tue Jul 30, 2013 5:25 pm Reply with quote

D_Hailsham wrote:
ashneedham wrote:
Don't know what the motorised valve is?

There are two types - see pics:

Login to view this image Login to view this image

There will be one (left pic) or two (right pic), probably near the pump.

You open the valve by moving the lever in the slot to the MAN end. It then locks by catching in the "nick" or pushing in/out, depending on make of valve


There are no motorised valves in the system.

Kind regards
Ash
Back to top
 Alert Moderators
ashneedham

from United Kingdom

Joined: 30 Jul 2013
Posts: 11
Location: Derbyshire,
United Kingdom

PostPosted: Tue Jul 30, 2013 5:29 pm Reply with quote

CBF wrote:
It's most likely an air lock, turn off all the rads upstairs & turn off the hot water on the programmer (if you can) if all the downstairs rads don't get hot then turn off the ones that do & that should force it round the others, if both ends of the upstairs rads are fully open you need to balance the system, try turning the locksheild rad valves (upstairs) so it's only open 1 1/2 turns that's a good starting point


Hi CBF,

We are getting no heat in any of the down stairs radiators. We tried turning off all the upstairs and left it for a good 20 mins but still the downstairs rads were cold.

Regards
Ash
Back to top
 Alert Moderators
D_Hailsham

from United Kingdom

Joined: 18 Oct 2007
Posts: 8713
Location: Sussex,
United Kingdom
Thanked: 1002 times

PostPosted: Tue Jul 30, 2013 6:24 pm Reply with quote

ashneedham wrote:
There are no motorised valves in the system.

Do you have a hot water cylinder?
How many pipes connect to the boiler - ignoring the gas pipe?
Which boiler do you have (make and model)?
Back to top
 Alert Moderators
ashneedham

from United Kingdom

Joined: 30 Jul 2013
Posts: 11
Location: Derbyshire,
United Kingdom

PostPosted: Tue Jul 30, 2013 7:18 pm Reply with quote

D_Hailsham wrote:
ashneedham wrote:
There are no motorised valves in the system.

Do you have a hot water cylinder?
How many pipes connect to the boiler - ignoring the gas pipe?
Which boiler do you have (make and model)?


It's a glow worm fuelsaver mk 2.

There are two water pipes connected.

We do have a hot water cylinder

Kind regards
Ash
Back to top
 Alert Moderators
D_Hailsham

from United Kingdom

Joined: 18 Oct 2007
Posts: 8713
Location: Sussex,
United Kingdom
Thanked: 1002 times

PostPosted: Wed Jul 31, 2013 11:20 am Reply with quote

ashneedham wrote:
It's a glow worm fuelsaver mk 2.

There are two water pipes connected.

We do have a hot water cylinder

How is the temperature of the hot water in the cylinder controlled?
Back to top
 Alert Moderators
Agile

from United Kingdom

Joined: 26 Jun 2004
Posts: 52973
Location: London,
United Kingdom
Thanked: 3343 times

PostPosted: Wed Jul 31, 2013 11:48 am Reply with quote

If there were no motor valves then he must have a gravity hot water system.

Someone should check if his boiler permits that.

Tony
Back to top
 Alert Moderators
ashneedham

from United Kingdom

Joined: 30 Jul 2013
Posts: 11
Location: Derbyshire,
United Kingdom

PostPosted: Wed Jul 31, 2013 1:46 pm Reply with quote

Agile wrote:
If there were no motor valves then he must have a gravity hot water system.

Someone should check if his boiler permits that.

Tony


Although we have pipes going into the cylinder, we have never had hot water from the boiler. We have had to use the immersion heater.
Back to top
 Alert Moderators
Search this topic :: View previous topic :: View next topic  
Post new topic   Reply to topic    DIYnot.com Forum Index > Plumbing and Central Heating All times are GMT
Goto page 1, 2  Next
Page 1 of 2

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
Similar Topics   Replies   Views   Posted 
Maximum Heat Delivery via 22mm Backbone 4 320 Fri Jan 13, 2006 7:40 pm
28mm gas pipe anywhere on run ? to up the delivery 12 2180 Wed Jun 11, 2008 5:47 pm
Oil delivery driver bodged tank connector - opinion??? 8 620 Sat Oct 18, 2008 2:18 pm
Oil Boiler won't power up after oil delivery 3 60 Thu Feb 13, 2014 7:35 pm
Negative head shower disaster - help needed!!! 2 880 Thu May 13, 2004 3:52 pm


 
DIYnot
Find an Expert | Find a Supplier | Search DIYnot.com
Network | Advertising | Newsletter
DIY | DIY How To | @home | DIY Wiki | DIY Forum
By using this site you agree to our Terms of Service / Disclaimer.
Please read our Privacy Policy. Copyright © 2000-2014 DIYnot Limited.