Water tank thermostat

[TP]

Hi all

Complete newbie to this group, so sorry if this is one you get every other week (though a quick look on Google groups doesn't reveal anything immediately identical).

- For about 8 months of the year, we run our hot water and heating off an oil-fired Rayburn. Does the trick, rarely needing to use the immersion heater unless we have a house full of in-laws.

- For the other four, the Rayburn's off, and we rely on the immersion entirely for hot water, using a (recently replaced and apparently functioning) timeswitch.

- This summer, for the first time, the water has been very hot - much hotter than we need or like, and a danger to our small children.

- This follows the replacement of the immersion heater element during the winter.

- I have adjusted the Honeywell thermostat on the side of the tank to no avail.

Questions:

- Is the replacement of a 20 year old heater element likely to result in

*such* a vastly improved performance that it potentially scalds everyone in the house with alarming regularity? (I guess so, but thought I'd check).

- Does the the tank thermostat typically control the immersion heater (rather than just the pump from the stove)? In other words - is it possible/likely the thermostat's broken.. or am I playing with something which is outside the circuit anyway?

- While looking at the tank thermostat, it appears to be wired only to a mains junction box on the wall and strapped to the tank under the lagging. Is there typically further electrical gubbins behind the thermostat and lagging controlling either the immersion or boiler feed? If not, how does it work?

- If the thermostat is broken, is it an easy job to replace for a bloke with a screwdriver and enough nous to turn off the mains? Any online resources?

Hope that's enough to give you some food for thought.. many, may TIA to anyone who can help - and fire away if I can assist with any more info.

TP

[Adrian Brentnall]

Sounds as if this stat is controlling the pump from the stove...... which is, as you say, nothing to do with your electric immersion heater. To prove this - you should be able to feel or hear the point at which the stat custs in / out while you tweak it ..... get an assistant to watch the electricity meter with the Immersion heater switched 'on'. If the stat you're twiddling is turning the immersion on & off then you should see the meter speed up / slow down accordingly.

If you turn off the power to the immersion heater, and undo the cover where the wires go in - you should see that there's a thermostat biult into the immersion heater - probably adjustable with a screwdriver....? Try turning this down. Don't pay too much attention to the actual temperature marked on the dial - but adjust it until it's right for your needs. Our electric immersion is at the bottom of our (larger than standard) hot water tank - so if you set it for 60 centrigrade at the bottom of the tank it's way too hot at the top...

Hope this helps Adrian Suffolk UK ======return email munged================= take out the papers and the trash to reply

[Grunff]

This is the key question. The heater element is controlled by the immersion thermostat, which is accessible under the heater element cover. When the element was replaced, the new thermostat was set much higher than the old one.

Remove the element cover, and set the thermostat to say 65C.

[Chris McBrien]

Dead right there. =

The thermostat is connected in SERIES with the immersion heater element so that it op= ens the circuit when the preset temperature is reached.

When I did my central heating I did read that 67=C2=B0 should be the maximum as this was= considered 'SCALDING'.

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[TP]

Hey - thanks guys.

I love usenet :)

[BigWallop]

Welcome to the group TP.

The thermostat held on the side of the hot water cylinder with a spring cord normally controls the boiler function side of things, and you should find that the electric heating side is controlled from a rod stat' that slides down a tube in the middle of the electric heating element itself.

If you turn the power off to the immersion, making sure it is properly off on both live and neutral sides, and lift the red cap off the element. You will see a little plastic box that has temperatures printed on it. It is more likely this stat' that is controlling the electrical side of the water heating. A simple firm but gentle press with your thumb or finger on the little wheel in the middle will allow you to adjust to the temp' you want.

Good luck with it.

[Christian McArdle]

That controls the Rayburn.

The immersion thermostat will be under the cap on the heater itself. On a modern installation, there should be two. One will have just a temperature setting. The other will have a reset button, and may or may not have a temperature setting. An older one will have only one thermostat with no switch.

Set the one with just a temp setting to between 55C and 60C. The other one (if adjustable and existent) should be set at around 75C.

Christian.