Replacing DHW / PHE Sensors

Hi there,

Also suffering from intermittent hot water - from reading this useful blog seems as though I need to replace the DHW sensor as a wiggle of this seems to sort out the problem each time i cant get any hot water.

My confusion is that the DHW sensor seems to be identical to the lower PHE sensor - and certainly different to the spare part DHW sold for the Pulsacoil 2000. Wonder if this is how some of these are wired and I should replace the DHW sensor with a PHE sensor - or if it has been wrongly fitted and I need to exchange it for the correct DHW sensor. I live in a hard water area so would a scrub of the sensor to descale it do the job?

Also, when it comes to fitting the new sensor, could you give an outline of the most important steps - there seems to be white sticky material holding sensors in place and wondering if there is a little more to getting the correct fit than im bargaining for..

Many thanks ineed

Hi

The DHW an PHE sensors on the Pulsacoil 2000 are very different.
The DHW sensor is in a wet pocket, but the PHE sensor is in a dry pocket. Neither will fit the other.

The "white sticky stuff" is a heat sink compound an shouldn't be wiped off as it is needed to help transfer the heat through to the sensor.

I would advise that you get an experienced Gledhill repair specialist to look at your unit.

Many thanks - the wet / dry pocket difference was what was confusing me. I spoke to Glenhill and in fact some of the pulsacoil 2000s have two dry pockets, as does mine, effectively meaning I need two of the PHE type sensors..

As im fitting a new sensor I guess I need to apply this heat sink compound for it to work effectively?

Anything else I need to be aware off?! I was just planning to turn of the power and replace the sensor which looks pretty straight forward?

Hi

There's nothing too complicated in replacing the dry sensors, but please make sure that you turn off ALL of the power supplies to the unit as there are often THREE INDEPENDENT POWER SUPPLIES before you take off the front cover.

Pay special attention to the way in which the sensors are connected at the circuit board end as the blue wires are NOT joined together.
Get a fresh tube of Regin heat sink compound to replenish the paste that is on the sensors. This is available from most branches of Parts Center and will cost about £12.00