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Topic Title: Central Heating Pump
Topic Summary: Runs continuously
Created On: 02 July 2013 09:11 PM
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 02 July 2013 09:11 PM
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Avatar for Rulland.
Rulland

Posts: 481
Joined: 11 April 2008

Evening All,
Just a quick question, I have a combi boiler running underfloor heating downstairs and rads upstairs, the pump, adjacent to the UFH header, runs continuously, even with the heating turned off, wiring incorrect?.
Cheers.

-------------------------
Those who make no mistakes do very little work!!......
 02 July 2013 09:24 PM
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sparkingchip

Posts: 6329
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Is there two pumps, if so which one keeps running?
 02 July 2013 09:39 PM
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SKElectrical

Posts: 911
Joined: 01 February 2009

If it is indeed the central heating pump running continuously then it is probably wired wrongly. It's dead easy it should come DIRECTLY off the pump connections in the boiler. If it is wired correctly to this then sounds like it's a fault with the boiler overrun (not sure if they are temperature controlled or time controlled).


Are you sure you're not looking at the pump for the U/F heating manifold (although I have to admit I've only seen them on the manifold itself)
 02 July 2013 10:30 PM
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Avatar for Rulland.
Rulland

Posts: 481
Joined: 11 April 2008

Thanks for the prompt replies guys-the pump is directly before the manifold-which has four sets of pipes in and out, three for the underfloor zones, kitchen, lounge and hallway, these have some sort of electric actuator on the tops of them wired to a large wiring box, the fourth I'm assuming must head upstairs to rads hasn't, just a manual valve.
Not really had much experience with this sort of setup, more an S-plan, or Y plan tbh.
It's the only pump I can see-or hear, I'll take a piccy of the setup-quite a few valves and flow gauges etc, tomorrow when theres more light.

-------------------------
Those who make no mistakes do very little work!!......
 02 July 2013 10:43 PM
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SKElectrical

Posts: 911
Joined: 01 February 2009

It sounds like it's the U/F manifold pump. if so then it should only run when demand for heat, no overrun. Difficult to say if not seeing it. It's important to ask the designer really.
 03 July 2013 10:25 AM
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AJJewsbury

Posts: 11768
Joined: 13 August 2003

There'd usually be a UFH wiring centre somewhere (like http://www.heatmisershop.co.uk...230v-wiring-centre-p59 ) - there are different version for different types of controls (12V 'network' stats, 230V etc) - they usually have 230V outputs for each zone (which connect to the thermal actuators you have seen) and outputs to pump and CH boiler which should be active whenever one or more zones call for heat.

The pump running all the time could be due to a fault room stat, calling for heat constantly, or a jammed relay in the wiring centre, or of course a wiring fault.

A less common possibility is that 4-wire actuators are used (2 wires power the actuator, the other two are a switch that closes when the actuator is active) - each room stats control an actuator directly then the switch wires are paralleled to control the UFH pump & call to boiler.

- Andy.
 03 July 2013 07:38 PM
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sparkingchip

Posts: 6329
Joined: 18 January 2003

You need the wiring instructions for the system, it could be blending water from the flow and return as the UFH runs cooler than radiators and be controlled by pipe sensors rather than the boiler.
 05 July 2013 10:52 AM
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rocknroll

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I think you will find in wet UFH multizone systems the circulation pump (not the central heating pump) is designed to run 24/7 at a set point governed by the ECU which is programmable for some good reasons which I will comment on in a bit, I have a 8 zone wavin/osma UFH supplied and commissioned by an excellent company in Welsh Wales and the circulation pump by default runs all the time at a set point of 10 degrees, I have mine set at 16 degrees 24/7 and it uses hardly any gas or electricity in this mode, the reasons for this are economy as it is far easier to raise the heat in a particular zone in minutes if the water is continuously circulating rather than stop start which can sometimes take 30 minutes or more if allowed to go too cold, the other problem is UFH systems do suffer from air-locks which result in hot and cold zones if the water is not kept circulating, if you examine the BMS in shopping malls, stores, offices etc who have wet UFH you will see that during the off-peak period the circulation pump will run 24/7 at a set point so that on-peak when the temperature is raised it will operate very quickly.

If the customer wants it to switch off completely well this can be done by entering the program that controls it.

regards

-------------------------
"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
-------------------------
 05 July 2013 11:09 AM
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OMS

Posts: 19900
Joined: 23 March 2004

supplied and commissioned by an excellent company in Welsh Wales


LoL - you buggers have been expecting the Welsh to get you out of the **** since Agincourt - everything we do is excellent -

Regards

OMS

-------------------------
Failure is always an option
 05 July 2013 11:17 AM
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rocknroll

Posts: 8905
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Originally posted by: OMS

supplied and commissioned by an excellent company in Welsh Wales


LoL - you buggers have been expecting the Welsh to get you out of the **** since Agincourt - everything we do is excellent -

Regards

OMS


LOL It does have some failings but I have to give credit where credit is due.

regards

-------------------------
"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
-------------------------
 05 July 2013 11:24 AM
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Avatar for OMS.
OMS

Posts: 19900
Joined: 23 March 2004

LoL - spoken like a true son of Empire - serve and obey

OMS

-------------------------
Failure is always an option
 05 July 2013 01:53 PM
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Avatar for rocknroll.
rocknroll

Posts: 8905
Joined: 03 October 2005

LOL Your mirth and Zs is much appreciated as I once again lounge on the patio feeling sorry for myself, just knocked up a nice crispy bacon and sausage sandwich on the gas barby, killing time by pinging a few seagulls in the butt with my somewhat underpowered air pistol who gather on the summer house waiting to pounce even into the conservatory on anything relating to food, might break out the .22 later and take a few out, got to be a bit careful down here as there are too many seagull appreciation society's and even an MP who thinks that an increase from 3.5m to now nearly 6m is okay,

Cant drive for another four weeks and although my car has been returned after the saga as you know its tracked so cant move it, the 2 sets of keys for my own car have mysteriously disappeared and I suspect the other half has them at her Pharmacy at Mayfield in case I sneak orf down the marina.

RnR going slowly mad, the best I felt was the two days when they sent me home with some morpine patches that only lasted two days could have done with a few weeks worth to relieve the boredom. LOL

regards

-------------------------
"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
-------------------------

Edited: 05 July 2013 at 02:03 PM by rocknroll
 05 July 2013 05:32 PM
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Avatar for OMS.
OMS

Posts: 19900
Joined: 23 March 2004

Get yourself off down the local slug and circuit-board, old chum - there's bound to be a good part P V gold club EICR debate you can join in ?

If the seagulls are playing up, I 'll send down a nice FAC Theoben gas ram in 0.20" with a good scope - the don't like that, at all - if you want to get serious, there's a nice silenced 0.410" smooth bore as well - that's a bit messy though

You just need to listen to Memsahib - she probably wasn't kidding when she told you take it steady and stashed the keys away to make sure you did - so listen up, yes !!

Have a good one and enjoy the sun - you're in the right place for it.

Regards

OMS

-------------------------
Failure is always an option
 07 July 2013 10:41 AM
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Avatar for slittle.
slittle

Posts: 3596
Joined: 22 November 2007

I have seen simple systems where the UFH pump is controlled by a pipe sensor on the manifold. When the incoming flow to the manifold from the heating system reaches temperature the pump starts up.

Found one before where the sensor had stuck closed so might be worth a look.

Or it could just be wired up wrongly, I've seen a few with the two wire actuators and no controller, the pump has then been stuck across the live supply as whoever installed it couldn't find anywhere better to put it.

Stu
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