Relocating Air/Water Heat Pump

[marlawesty]

I need to have my swimming pool heater relocated by around 20 metres from its current position, along with the circulation pump and a timeclock. At present the Heat Pump has its own 32A feed direct from Fuse Box and the Circulation Pump runs off a separate feed.

I have removed a Dehum unit which was in the pool house supplied by a 16A feed (2.5mm wire). This is a few meters from the new location of the Heat Pump

I was wondering whether I could join the existing 6mm armoured cable to the 2.5mm armoured cable, de-rate the supply to 20A, and finally extend the existing cable to the Heat Pump and Circulation pump. I estimate the total run from box to heat pump to be less than 50M. Total load is 3.3KW for Heat Pump/Circulation pump.

I know the cleaner solution would be to run the 32A cable all the way but I was wanted to know if there was anything I need to consider if I go the other route? All the work would carried out by a qualified electrician.

Finally do I need building regs if I am relocating?

 

[ericmark]

All the work would carried out by a qualified electrician

So let him advise, he has to sign to say he has designed, installed and inspected and tested, so he must design it, not a group of people on a forum.

There is a lot to consider, a heat pump is basic a refrigeration unit, the motor needs to reach full speed before the pressure builds up or it will stall with a single phase motor, one way around the problem is using an inverter drive, but the inrush is some thing which needs to be taken into consideration. The same applies to volt drop, again because if it can't start fast enough it can stall.

Often you also need a type other than type B for the supply MCB, and depending on the type, is the loop impedance upper limit, and the loop impedance meters cost around £200 so your not going to know how close to the wind you are sailing until the electrician takes the measurements.

Current capacity of electric cable varies depending on how installed, so same cable may be good for double the current in one installation to another, and also type of cable, thermal plastic, thermal setting, and mineral insulated all have different current ratings.

Swimming pools are a special location, and one has to be careful what supplies are used, it is very much down to location and earthing or bonding systems in use, we have to consider what happens with a loss of PEN, no point in explaining what the PEN is, as you will not have the ability to work out if a TN supply is TN-S or TN-C-S without the supplier telling you.

So without being on site and noting what is installed already and making readings, can't answer that question, you need to let the electrician advise you.