Crankcase heaters on splits?

[Makeit go Right]

On larger fridge systems, (chillers and the like) one always finds a crankcase heater but on lots of the splits there are none. I presume on the comfort-type systems they are not expected to operate in the winter so they do not need that kind of protection.

However, heatpumps start up in the cold so one would expect crankcase heaters on all of them - I know at least one or two of the Daikins do have crankcase heaters in their condensing units but not all of them AFAIU.

Anyone know why it is okay to not have crankcase heaters on heatpumps? How do they design around this situation?

[Brian_UK]

Sorry, most of the kit that I have seen had crankcase heaters on them; Daikin, Mitsi etc.

Mind you things may have changed, I haven't seen much 'new' equipment for a while.

[sinewave]

Off Topic I know, but Brian have you been to Monkey World in Dorset?


If so is it worth a Trek to go as the Mrs and little un are big in to Urangatans!

[monkey spanners]

The fujitsu unit i droped the earth screw in today had a cch, i saw it when i striped it down to get the screw back
Have heard that some inverter units run a small current through the compressor winding to keep it warm.

[Thermatech]

Cheap brands have no crankcase heater to keep cost low in many cases they do not have basic safety controls such as LP swich,HP switch or low ambient control also to keep cost low.
If you think these items are preferable then you have to trick out the unit yourself.
On premium brands most of these items are built in as standard hence extra cost.
Also some premium brands include an oil seperator on comp discharge ensuring imediate oil return to comp suction even if some oil is flushed out on start due to liquid refrigerant in oil. Again this is a delux item not found on basic cheap splits.
Compressor bearings are also part of the story. Cheap mild steel bearings will be damaged if run with no oil. More expensive stainless steel bearings can tolerate some lack of oil running without any damage.

I did hear some argument that with R410a there may be no need for crank case heater but i am not sure about that idea because with our winter ambient conditions I still think liquid refrigerant can end up in comp oil during off period.
As a precution CCH is best option for splits.

[cool#9]

Hi everyone, very interesting to read and maybe you'll also agree with this:
1st: on small split units with rotary cp and accumulator, the total refrigerant amount charge is too low to create problem inside the crankcase.
Did you noticed we only find crankcase in bigger units ?
2nd: cp oils are very good at low ambient temp, both mineral and POE.
3rd: usually on inverter type the cp is warmed by the motor coils through the inverter power module.

I don't think it's only a matter of price, cause we just don't need it !!
rgds
cool#9

[Thermatech]

You make some interesting points.

Some small units do not have any accumulator , but anyway this will not stop refrigerant migrating to compressor shell during unit off & cold ambient condition.
If small units which are R410a & inverter drive have an oil warm up mode then why do other small units which are R410a & fixed speed compressor but do not have crankcase heater in place of oil warm up mode?

Be careful about oil warm up because on some larger VRF systems oil warm up is only activated when first power up outdoor unit & ambient temperature is very cold & unit is requested to run before crank case heater has been on 12 hrs to warm up oil.

Do the small inverter drive units monitor compressor shell temperature so as to know if oil needs warm up before compressor start ?

[cool#9]

Do the small inverter drive units monitor compressor shell temperature so as to know if oil needs warm up before compressor start ?

Hi Thermatech see attached file, first item, about daikin's inverter split/multi (R22).
rgds
cool#9

[Thermatech]

Good one Cool#9.

Do the R410a Daikin inverter heat pump splits have the same oil warm up safety function ?

Do you know any other manufacturers use this type of oil warm up mode on small inverter heat pump split systems ?

I wonder why any manufacturer would include this protection mode on inverter models as standard but not include any crankcase heater on the same size fixed speed heatpump models ?

Perhaps someone would care to comment.

[cool#9]

Good one Cool#9.

Do the R410a Daikin inverter heat pump splits have the same oil warm up safety function ?

Hi Thermatech
See attached file about inverter multi R410A "E" series.
Sorry don't know much more about other brands as i work at 90% with daikin, but i'd be please to know how the others do.
rgds
cool#9