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Hi guys.

I live in a bungalow with 14 radiators.

Closed loop heating system

The heating is zoned so that individual areas or hot water can be independently heated.

All radiators and heating cylinder are at ground level.

My boiler is 7 meters away from the house in the garden. 11 meters from the heating manifold.

Pipes from boiler to main manifold are 1 inch pipes.

This may or may not be my problem.

I installed a new boiler. Complete with circulating pump.

The new circulating pump does not flow sufficiently around the house.
Even if I only run it through the hot water cylinder only. (shortest route)

The pump has a 5 meter head.

I installed my old pump. And it works fine. 7 meter head.

A couple of years ago. The original pump in the boiler failed. I purchased a standard pump and it didn't work.

The plumbing supplier suggested the 7 meter pump. That's how I got the 7 meter head pump

The lines are clean and flow well.

Is there a problem with my heating system. Or is it normal for some small heating systems to have a bigger pump.

Thanks in advance.

Vince
 
What boiler is it now?
It's a new Firebird silver pack 26kw.

I think I have an idea of what has happened.

The original pump that was in my original boiler. Must have been a high flow pump.

Based on this pump. I balanced the heating system.

Been working fine for the last 15 years.

After this post. I rebalanced the hot water cylinder. And the performance of the heating improved.

I have multiple sensors attached to my heating system. And am able to
See more temperature graphs than would be necessary.

Is it normal to rebalance after changing circulating pump?
 

Attachments

14 radiators in a bungalow must be a large system.
Really to get an exact answer you need to do some maths to find out minimum flow rate and maximum pressure required. If you can circulate around the index circuit (loop with greatest pressure loss) then you can circulate around everything else as well.
As Simon says above what boiler and size is it now? What I'm assuming hes getting at and what I'm wondering is if it's not been sized correctly.
 
14 radiators in a bungalow must be a large system.
Really to get an exact answer you need to do some maths to find out minimum flow rate and maximum pressure required. If you can circulate around the index circuit (loop with greatest pressure loss) then you can circulate around everything else as well.
As Simon says above what boiler and size is it now? What I'm assuming hes getting at and what I'm wondering is if it's not been sized correctly.
The boiler is a direct replacement for the last one. Only that it's the new condensing type.

Old boiler Firebird kabin pack 70/90 26kw

New boiler Firebird silverpack 26kw

The system is working well at the moment with my old pump.

I will add pressure sensors to the system and monitor the system on my home auto.

Thanks for the advice
 
The pump has a 5 meter head.

I installed my old pump. And it works fine. 7 meter head.
You need the displacement rate as a function of head to to specify a pump. The 'head' on its own is not enough. Which models of pumps have you tried? Most modern central heating pumps are 'smart', i.e. have several speeds and modes of operation. The mode needs to be matched to the system.
 
Last edited:
Hi guys.

I live in a bungalow with 14 radiators.

Closed loop heating system

The heating is zoned so that individual areas or hot water can be independently heated.

All radiators and heating cylinder are at ground level.

My boiler is 7 meters away from the house in the garden. 11 meters from the heating manifold.

Pipes from boiler to main manifold are 1 inch pipes.

This may or may not be my problem.

I installed a new boiler. Complete with circulating pump.

The new circulating pump does not flow sufficiently around the house.
Even if I only run it through the hot water cylinder only. (shortest route)

The pump has a 5 meter head.

I installed my old pump. And it works fine. 7 meter head.

A couple of years ago. The original pump in the boiler failed. I purchased a standard pump and it didn't work.

The plumbing supplier suggested the 7 meter pump. That's how I got the 7 meter head pump

The lines are clean and flow well.

Is there a problem with my heating system. Or is it normal for some small heating systems to have a bigger pump.

Thanks in advance.

Vince
Can you post the name & exact model number of both pumps and the present setting of the installed old 7M pump, it is a bit surprising that the 5M one couldn't even circulate the cylinder coil only, as stated above it may have been set up in the wrong mode. Some A rated (only ones available now) are rated as 4M/7M pumps so if you know the old pump make/model it should be relatively easy to choose a replacement when/if your old one packs up.
 
Just looking at those numbers again, 11M (22M total) of 1" (irish) piping will only drop ~ 0.5M assuming a flowrate of 20 LPM, a Dab Evosta 4-7M pump will give a head of 4.3M at this flowrate on speed 3 and 3.2M at speed2 which corresponds fairly closely to a 5M pump, a Wilo Yonis Pico 5M will give a head of 3.6M (at 20 LPM). One might think that this head even with a 5M pump might be sufficient and would certainly think that a 6M pump would be quite adequate under normal circumstances.
 
Just looking at those numbers again, 11M (22M total) of 1" (irish) piping will only drop ~ 0.5M assuming a flowrate of 20 LPM, a Dab Evosta 4-7M pump will give a head of 4.3M at this flowrate on speed 3 and 3.2M at speed2 which corresponds fairly closely to a 5M pump, a Wilo Yonis Pico 5M will give a head of 3.6M (at 20 LPM). One might think that this head even with a 5M pump might be sufficient and would certainly think that a 6M pump would be quite adequate under normal circumstances.
Everything you say john mate adds up but unless we have a full description of pipe runs, size of pipes off main branch, total fittings and resistance of boiler and all rads then theres no real way to determine the head and flow required.
 

king of pipes

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Dab Evosta will cover what you need i regularly use them i have one installed on a 3 storey 14 rad system it is running on full speed in the heating season, but can be adjusted for summer use to heat the the unvented cylinder.
As others have advised pipe size lenth of run and height all have a effect on flow rate as will balancing of the lockshields .kop
 
Everything you say john mate adds up but unless we have a full description of pipe runs, size of pipes off main branch, total fittings and resistance of boiler and all rads then theres no real way to determine the head and flow required.

I just assumed a few things, that the boiler is oil fired (externally installed) which will have a very low deltaP and that the installed rads have a total output of ~ 21 kw which would require a flow rate of 20 LPM @ 15C deltaT, the most intriguing point is that the 5M pump couldn't even circulate the hot water cylinder coil?.
 
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I just assumed a few things, that the boiler is oil fired (externally installed) which will have a very low deltaP and that the installed rads have a total output of ~ 21 kw which would require a flow rate of 20 LPM @ 15C deltaT, the most intriguing point is that the 5M pump couldn't even circulate the hot water cylinder coil?.

Yes that is a surprise that a 5M couldn't even circulate around the HW circuit, you would expect that circuit to be minimal pressure drop.
 
Just saw post #7 there now (could have sworn that it wasn't there earlier on) so it is a oil boiler which the manual states has a negligible water side deltaP of 0.18 mbar.
 

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