how to replace sensor

Hi,

My pulsacoil 2000 boiler gives me fluctuation hot water. I have had this problem in the past and is normally solved by replacing either or both sensors.
Normally i get someone out to do this but want to save the call out fee.

I have a spare brand new T1 DHW sensor (screw type GT153) but how do I fit this? After turning the main water off quite a lot of hot water came out of the sensor so I quickly replaced it, is there another place I should turn off the water?

Err nope. Just turn OFF the mains water stopcock and you should be abale to change the DHW sensor with minimal water loss. Try opening a hot tap to relieve the pressure.

You ARE unscrewing the DHW sensor not the PHE return sensor, aren't you?

Cheers, Mike

am I right in thinking the PHE return sensor (GT146) is not a screw type at all? That one is easy to replace, however where do I get a spare one of those?

When I unscrewed the DHW sensor (after turning off main stopcock) hot water came out, which made me concerned I had forgot to turn someting off.
I'll try again, but what is a normal amount of water loss?

Hi juniper,

Yes the GT146 sensor is 'dry pocket' and consequently dead simple to fit with no turning OFF of water required. Gledhills sometimes have the GT153 wet pocket sensor used for the PHE return sensor though, same as the DHW sensor.

I would normally expect NO water at all to come out when removing a DHW sensor, or just a tiny trickle. Little enough to catch with a towel easily. Did you turn a hot tap ON to check you have successfully isolated the water supply? If you still get water from the hot tap then you KNOW you haven't turned the water OFF correctly. Or are you saying you get NO water from the hopt tap but you still get water from the sensor hole?

Make sure you turn the hot tap OFF again before taking out the sensor or air will enter it (if it is higher than the Pulsacoil) and allow water to pour out of the sensor hole. Maybe this is the reason.

Or if the pressure is low you just take the old one out and quickly screw in the new one, ignoreing the water flow.

Thanks Mike,
It was tap turned that off and no problem replacing gt153
Where can I buy a new gt146 sensor?

Try www.segel.co.uk

Cheers, Mike