Temperature control switch wiring

[OllyO]

I'm wiring in a temperature control switch to operate a pump for our central heating system run off our back boiler.

just wanted to double check before I went ahead that I'm going to wire it correctly.

It's clear where the +/- terminals are but would I be correct in saying the terminal marked 'relay contact' should go to the pump so that it is activated are the set temperature? 

[Ex Brummie]

What temperature are you measuring? Not a stupid question, as if you measure room temperature, you do not want the pump to switch on unless the water is hot enough to circulate. Once you start pumping, the backboiler temperature can fall quickly, so you need to switch off the pump to allow the water to heat again. Personally, I use a clamp on pipe stat on the boiler flow pipe, with a live feed to the common terminal, and a switched feed from the normally open contact to the pump (then neutral to the pump). Setting the thermostat to 60c-65c means the pump starts to circulate when the boiler reaches 60-65, but cuts out when the temperature falls. You don't want to circulate cold water in the radiators, (or calorifier where you will cool your hot water). Measuring room temperature is pretty pointless, as you won't have your fire lit unless you want it.

[nicknorman]

K0 and K1 is a switch - connected together when turned on. So probably you need to connect K0 to the pump, K1 to the power source for the pump, and of course the other connection on the pump to negative/ground. So that when the relay is on, power flows from the supply through K1 and K0 to the pump and then to ground.

2 minutes ago, Ex Brummie said:

What temperature are you measuring? Not a stupid question, as if you measure room temperature, you do not want the pump to switch on unless the water is hot enough to circulate. Once you start pumping, the backboiler temperature can fall quickly, so you need to switch off the pump to allow the water to heat again. Personally, I use a clamp on pipe stat on the boiler flow pipe, with a live feed to the common terminal, and a switched feed from the normally open contact to the pump (then neutral to the pump). Setting the thermostat to 60c-65c means the pump starts to circulate when the boiler reaches 60-65, but cuts out when the temperature falls. You don't want to circulate cold water in the radiators, (or calorifier where you will cool your hot water). Measuring room temperature is pretty pointless, as you won't have your fire lit unless you want it.

It does have a remote probe, presumably this will be attached to the pipe.

[Ex Brummie]

And don't forget to set the correct mode which, if you are controlling the pump on flow temperature, will be cooling.

[Chewbacka]

It's not clear from the device information the current rating of the on board relay, so worth checking it's enough to switch the pump.

[rusty69]

8 minutes ago, Chewbacka said:

It's not clear from the device information the current rating of the on board relay, so worth checking it's enough to switch the pump.

If not could it be used to switch an automotive type relay? 

[Chewbacka]

21 minutes ago, rusty69 said:

If not could it be used to switch an automotive type relay? 

Yep, most definitely. 

[Ex Brummie]

10 amp switch, according to the full data sheet. Priced cheaper than a normal pipe stat, but would need an enclosure and looks fiddly.

[OllyO]

Yes, probe measures pipe temp and would be se correctly.

Might be me but I can't find pipestats online, anyone got a link?

This type look good but only in US?

https://www.google.co.uk/search?q=pipe+thermostat+switch&safe=off&client=safari&hl=en-gb&prmd=sivn&source=lnms&tbm=isch&sa=X&ved=0ahUKEwituJC-hoTYAhVKKFAKHbCnAuUQ_AUIEigC&biw=320&bih=460#imgrc=hHODElNTYn43TM:

[Chewbacka]

2 hours ago, OllyO said:

Yes, probe measures pipe temp and would be se correctly.

Might be me but I can't find pipestats online, anyone got a link?

This type look good but only in US?

https://www.google.co.uk/search?q=pipe+thermostat+switch&safe=off&client=safari&hl=en-gb&prmd=sivn&source=lnms&tbm=isch&sa=X&ved=0ahUKEwituJC-hoTYAhVKKFAKHbCnAuUQ_AUIEigC&biw=320&bih=460#imgrc=hHODElNTYn43TM:

Some hot tank stats will work as pipe stats.  The simple bi-metal strip type don't care about the supply volts, but a fancy digital one will require 240v ac to power up the electronics.  Suggest you have a look on the screwfix web site.  Just look for "cylinder thermostat".

 

 

Edited December 12, 2017 by Chewbacka

[Ex Brummie]

Screwfix Flomasta Cylinder stat is adaptable for a pipe.

[adrianh]

Any pipe stat will do the job although a bit ugly if you can see it. Alternative is a capillary thermost as used on older boilers rs733 4723 or similar. Non of these are deigned for a DC load so add a back emf diode across the contact or pump to reduce arcing when it turns off

[cereal tiller]

On 12/12/2017 at 10:34, Chewbacka said:

Some hot tank stats will work as pipe stats.  The simple bi-metal strip type don't care about the supply volts, but a fancy digital one will require 240v ac to power up the electronics.  Suggest you have a look on the screwfix web site.  Just look for "cylinder thermostat".

 

 

12 Volt Digital  Stats are around ,'bout 12 Quid from Ebay ,and Panel mount too.

[smileypete]

There's thermal switches on Ebay for a couple of quid.

Maybe have one to start the pump running slowly at 60°C, then another to run the pump fast at 90°C.

Usually they switch back at 10 to 15°C lower.

Or use the dig thermostat to start the pump running slowly at a lower temp then have a 80°C to 90°C thermal switch as a backup.

Edited December 13, 2017 by smileypete