# Oil boiler thermostat v hot press thermostat



## BarneyMc (3 Dec 2008)

I have my oil boiler thermostat set to 40C but just noticed a thermostat in my hotpress and it is set to 90C. The hotpress tank is hot from top to bottom with really hot water (bit of a waste I think). I usually just use my oil boiler and don't bother lighting a fire where my back boiler is.

1. Is the thermostat in my hotpress for a circulation pump and is it for my back boiler or to do with my oil boiler?
2. Should the thermostat in my hotpress be set to 90C if my boiler thermostat is set to 40C?
3. How should I alter these thermostats so the tank in the hotpress does not have to be fully heated and therefore save some oil?


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## DavyJones (3 Dec 2008)

BarneyMc said:


> I have my oil boiler thermostat set to 40C but just noticed a thermostat in my hotpress and it is set to 90C. The hotpress tank is hot from top to bottom with really hot water (bit of a waste I think). I usually just use my oil boiler and don't bother lighting a fire where my back boiler is.
> 
> 1. Is the thermostat in my hotpress for a circulation pump and is it for my back boiler or to do with my oil boiler?
> 2. Should the thermostat in my hotpress be set to 90C if my boiler thermostat is set to 40C?
> 3. How should I alter these thermostats so the tank in the hotpress does not have to be fully heated and therefore save some oil?



1, yes it reads flow water temperture from back boiler. Once it reaches set temp it sends power to a pump, and that pumps water into rad system. When flow cools, it will stop pump.

2 They are two seperate systems. 90 is a bit high, turn it down to maybe 60.

3 turn down thermostat


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## BarneyMc (3 Dec 2008)

Thanks for the info DavyJones.

So if I'm just using the oil boiler the only control I have is to turn down the thermostat on the oil boiler?


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## DavyJones (3 Dec 2008)

BarneyMc said:


> Thanks for the info DavyJones.
> 
> So if I'm just using the oil boiler the only control I have is to turn down the thermostat on the oil boiler?



Yes, assuming your system has been designed correctly. you may also have room stats or thermostatic rad valves fitted?


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## DGOBS (3 Dec 2008)

Should not both stats be set to above 60degs as to avoid possible legonella froming in you cylinder!

All newer stats I have come across only range from 60-90 for this reason


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## BarneyMc (4 Dec 2008)

DavyJones said:


> Yes, assuming your system has been designed correctly. you may also have room stats or thermostatic rad valves fitted?


 
No, the house is about 40 years old and nothing like this.

The thermostat in the hotpress seems to be hard wired to the switch for the oil. I did have a fire in my backboiler fireplace yesterday and the water seemed to be making noises. When I switched on the oil (this enabled the thermostat in the hotpress) the water noises cleared.

This would suggest the thermostat should not be hard wired to the oil switch as they are not associated in any way? It would also suggest I have to manually swich on the oil from time to time if the water in the back boiler gets too hot?


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## BarneyMc (4 Dec 2008)

DGOBS said:


> Should not both stats be set to above 60degs as to avoid possible legonella froming in you cylinder!
> 
> All newer stats I have come across only range from 60-90 for this reason


 
Not sure regarding legonella. 40C for my oil boiler is more than enough as it heats the house fine.


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## tosullivan (4 Dec 2008)

I have my boiler stat set for 65 and the one in my hot press for the tank immersion heater set for roughly the same, maybe 5deg lower


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## BarneyMc (4 Dec 2008)

tosullivan said:


> I have my boiler stat set for 65 and the one in my hot press for the tank immersion heater set for roughly the same, maybe 5deg lower


 
I don't think the stat in my hotpress has anything to do with my immersion... it's almost certainly to do with the pump (for the back boiler according to suggestions I'm getting)


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## DGOBS (4 Dec 2008)

but if your boiler stat is at 40degs then when heating you cylinder it can only reach 40degs max too (if even) and any stored water at below 60degs runs the legonella risk


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## tosullivan (4 Dec 2008)

DGOBS said:


> the legonella risk


 ??????????????


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## NOAH (4 Dec 2008)

that legionnaires disease ---

naoh


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## DGOBS (4 Dec 2008)

what's not to understand!
If you store hot/warm water at below 60degs bacteria have a field day
So then you jump into your nice warm shower and breathe in legionella spores and get either extremely sick or die

My wife is a water microbiologist and I have stuff like this beaten into me!


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## BarneyMc (4 Dec 2008)

What about low heat systems? I thought they all worked on this principal? I would think anyone with an open fire and back boiler as their only heat supply would have this problem? I have an electric shower which works from the cold supply I would assume?


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## DGOBS (6 Dec 2008)

Yes, any system that stores water at this nice warm temperature is keeping a breeding ground!

As for stives and back boilers, the heat there is excessive, hence the banging of pipes on pumped systems when the electricity goes!


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