Anti-freeze mode for ecodan ashp

DyfedWyn

This is my first winter with a Mitsibushi ashp. Now that the outside temperature has dropped to 5 degrees and below at times, anti-freeze mode is kicking in quite a bit. My question is should this be reducing the temperature of my hot water cylinder? It’s a brand new cylinder (installed as part of the eco4 scheme). I seem to have gone from the high 40s to the mid 30s overnight. There might be no connection between the two things, of course, but the hot water has lost as much temp before now.

Thanks

QrizB

Welcome to the forum.

I think what you're seeing is the anti-frost cycle. When it's cold and humid outside, the humidity from the air freezes on the heat pump evaporator and forms ice. If this ice is allowed to build up the heat pump will stop working, so every ao often it reverses and takes heat from the hot side (your water) to thaw the ice.

So yes, if you aren't heating your HW tank at the time, the tank will get colder as the heat is taken to melt the ice.

(If there are any Ecodan experts here, and not skulking in the "other fuels" or "green and ethical" forums, please feel free to correct me.)

MultiFuelBurner

We have blue glycol (anti freeze) in our system which can be seen when you bleed a radiator upstairs above the cream carpet (handy colour lol)

However we have left our defrost setting to 5oC as delivered (standard settings)

The defrost cycle will not use the immersion heater (so let's get that out the way first so no big bills).what it does is it simply runs the heat pump in reverse and temporarily extracts heat from the water flowing through your radiators in order to melt the ice that has accumulated on the outdoor unit. So you pay for the electric pump to run that process for 2 mins.

MultiFuelBurner

QrizB said:

Welcome to the forum.

I think what you're seeing is the anti-frost cycle. When it's cold and humid outside, the humidity from the air freezes on the heat pump evaporator and forms ice. If this ice is allowed to build up the heat pump will stop working, so every ao often it reverses and takes heat from the hot side (your water) to thaw the ice.

So yes, if you aren't heating your HW tank at the time, the tank will get colder as the heat is taken to melt the ice.

(If there are any Ecodan experts here, and not skulking in the "other fuels" or "green and ethical" forums, please feel free to correct me.)

Contrary to belief they do let us ASHP'ers out for good behaviour. I obviously escaped.

DyfedWyn

MultiFuelBurner said:

We have blue glycol (anti freeze) in our system which can be seen when you bleed a radiator upstairs above the cream carpet (handy colour lol)

However we have left our defrost setting to 5oC as delivered (standard settings)

The defrost cycle will not use the immersion heater (so let's get that out the way first so no big bills).what it does is it simply runs the heat pump in reverse and temporarily extracts heat from the water flowing through your radiators in order to melt the ice that has accumulated on the outdoor unit. So you pay for the electric pump to run that process for 2 mins.

Thanks for the response. The pump (not the ashp) seems to be on all the time the outside temp is 5 or below. Can this be right? My understanding (right or wrong) is that it keeps the water flowing so that it doesn’t freeze in ashp.

Spoonie_Turtle

DyfedWyn said:

MultiFuelBurner said:

We have blue glycol (anti freeze) in our system which can be seen when you bleed a radiator upstairs above the cream carpet (handy colour lol)

However we have left our defrost setting to 5oC as delivered (standard settings)

The defrost cycle will not use the immersion heater (so let's get that out the way first so no big bills).what it does is it simply runs the heat pump in reverse and temporarily extracts heat from the water flowing through your radiators in order to melt the ice that has accumulated on the outdoor unit. So you pay for the electric pump to run that process for 2 mins.

Thanks for the response. The pump (not the ashp) seems to be on all the time the outside temp is 5 or below. Can this be right? My understanding (right or wrong) is that it keeps the water flowing so that it doesn’t freeze in ashp.

This us what ours seems to do, except I'm not entirely sure at what external temperature it kicks in - the heating goes off at 11pm (we don't need it to be 18℃ at 3am, and without a setback function setting a schedule was the only option) but there's a pump cycling all night long.  Really annoying! 
We have glycol in the system but I've not yet dared find out what the defrost temperature is set to as it says it requires switching the system off.  It's too cold to risk that it won't restart properly, especially as we've had a couple of issues in the last year of it losing connection and not working.

MultiFuelBurner

DyfedWyn said:

MultiFuelBurner said:

We have blue glycol (anti freeze) in our system which can be seen when you bleed a radiator upstairs above the cream carpet (handy colour lol)

However we have left our defrost setting to 5oC as delivered (standard settings)

The defrost cycle will not use the immersion heater (so let's get that out the way first so no big bills).what it does is it simply runs the heat pump in reverse and temporarily extracts heat from the water flowing through your radiators in order to melt the ice that has accumulated on the outdoor unit. So you pay for the electric pump to run that process for 2 mins.

Thanks for the response. The pump (not the ashp) seems to be on all the time the outside temp is 5 or below. Can this be right? My understanding (right or wrong) is that it keeps the water flowing so that it doesn’t freeze in ashp.

If you have had weather like us today it didn't get above 2oC  and yes even when the heating and hot water is off the pump is still constantly circulating the water round. That includes to the outside unit.  

DyfedWyn

MultiFuelBurner said:

DyfedWyn said:b

MultiFuelBurner said:

We have blue glycol (anti freeze) in our system which can be seen when you bleed a radiator upstairs above the cream carpet (handy colour lol)

However we have left our defrost setting to 5oC as delivered (standard settings)

The defrost cycle will not use the immersion heater (so let's get that out the way first so no big bills).what it does is it simply runs the heat pump in reverse and temporarily extracts heat from the water flowing through your radiators in order to melt the ice that has accumulated on the outdoor unit. So you pay for the electric pump to run that process for 2 mins.

Thanks for the response. The pump (not the ashp) seems to be on all the time the outside temp is 5 or below. Can this be right? My understanding (right or wrong) is that it keeps the water flowing so that it doesn’t freeze in ashp.

If you have had weather like us today it didn't get above 2oC  and yes even when the heating and hot water is off the pump is still constantly circulating the water round. That includes to the outside unit.  

Yes this is exactly the situation - as I expected. What I didn’t expect was for the temp of the hot water in the cylinder to drop so much at the same time.

DyfedWyn

Spoonie_Turtle said:

DyfedWyn said:

MultiFuelBurner said:

We have blue glycol (anti freeze) in our system which can be seen when you bleed a radiator upstairs above the cream carpet (handy colour lol)

However we have left our defrost setting to 5oC as delivered (standard settings)

The defrost cycle will not use the immersion heater (so let's get that out the way first so no big bills).what it does is it simply runs the heat pump in reverse and temporarily extracts heat from the water flowing through your radiators in order to melt the ice that has accumulated on the outdoor unit. So you pay for the electric pump to run that process for 2 mins.

Thanks for the response. The pump (not the ashp) seems to be on all the time the outside temp is 5 or below. Can this be right? My understanding (right or wrong) is that it keeps the water flowing so that it doesn’t freeze in ashp.

This us what ours seems to do, except I'm not entirely sure at what external temperature it kicks in - the heating goes off at 11pm (we don't need it to be 18℃ at 3am, and without a setback function setting a schedule was the only option) but there's a pump cycling all night long.  Really annoying! 
We have glycol in the system but I've not yet dared find out what the defrost temperature is set to as it says it requires switching the system off.  It's too cold to risk that it won't restart properly, especially as we've had a couple of issues in the last year of it losing connection and not working.

I think mine kicks in at 5 degrees. 

Are you seeing the temperature of your hot water in the cylinder dropping? Mine loses about 10 degrees in a night it seems.

Reed_Richards

I do not have an Ecodan heat pump but I do have a heating system that incorporates a buffer tank.  When my heat pump wants to defrost, it uses the warm water in the buffer tank and doesn't rob the hot water from the radiators or the DHW cylinder. 

Spoonie_Turtle

DyfedWyn said:

Spoonie_Turtle said:

DyfedWyn said:

MultiFuelBurner said:

We have blue glycol (anti freeze) in our system which can be seen when you bleed a radiator upstairs above the cream carpet (handy colour lol)

However we have left our defrost setting to 5oC as delivered (standard settings)

The defrost cycle will not use the immersion heater (so let's get that out the way first so no big bills).what it does is it simply runs the heat pump in reverse and temporarily extracts heat from the water flowing through your radiators in order to melt the ice that has accumulated on the outdoor unit. So you pay for the electric pump to run that process for 2 mins.

Thanks for the response. The pump (not the ashp) seems to be on all the time the outside temp is 5 or below. Can this be right? My understanding (right or wrong) is that it keeps the water flowing so that it doesn’t freeze in ashp.

This us what ours seems to do, except I'm not entirely sure at what external temperature it kicks in - the heating goes off at 11pm (we don't need it to be 18℃ at 3am, and without a setback function setting a schedule was the only option) but there's a pump cycling all night long.  Really annoying! 
We have glycol in the system but I've not yet dared find out what the defrost temperature is set to as it says it requires switching the system off.  It's too cold to risk that it won't restart properly, especially as we've had a couple of issues in the last year of it losing connection and not working.

I think mine kicks in at 5 degrees. 

Are you seeing the temperature of your hot water in the cylinder dropping? Mine loses about 10 degrees in a night it seems.

I haven't particularly kept an eye on it, but I know it gets quite cool during the day anyway as it only heats up in the morning.  It's set to heat to 50℃ and the times I have noticed for whatever reason, it can be down in the teens by bedtime, especially this time of year.