Mitsubishi ecodan ASHP no heating

markin

Generally i don't hear the one up my road until its around 5C or below.

If its not maintaining 18c then the may be something wrong with it, Unless its 'set back' temp is 16c and then it takes hrs to warm back up? 


https://www.youtube.com/watch?v=RX31v4NoQf4

https://www.youtube.com/watch?v=uC3jydJydRQ

shinytop

UnicornGirl81 said:

markin said:

If it wasn't getting heat it would indefinably call for it, not turn off after 5min?

And as it’s mild the outside unit would not be working hard anyway.

It’s not particularly mild where I am it’s been around 10 to 12 degrees today so surely it should be working?

It was warmer outside when I moved in back on March and it worked perfectly fine then the thermostats were set to 20 to 22 degrees and 
the heat pump could be heard working every day. 

The thermostats are set to 25 degrees at the moment and the inside temperature of the house is currently 16 degrees so surely it should be kicking in?

If you haven't tried already, use the plus arrow to bump up that zero to 9 or 10 and see if the heating kicks in.  

Mstty

One more thing to check

What is you weather compensation heat curve temperature set to.

Some silly engineer may have set the top temperature of the curve at 20/21oC. When in reality it should be a minimum of 30-35oC for the weather at the moment.

UnicornGirl81

Mstty said:

One more thing to check

What is you weather compensation heat curve temperature set to.

Some silly engineer may have set the top temperature of the curve at 20/21oC. When in reality it should be a minimum of 30-35oC for the weather at the moment.

I clicked on the view button and this is what it’s set to…

Reed_Richards

markin said:

If it wasn't getting heat it would indefinably call for it, not turn off after 5min?

And as its mild the outside unit would not be working hard anyway.

If the water wasn't flowing properly then there might be a thermal cut-out after 5 minutes.  If there was a blockage in the central heating system then there could be flow to and from the buffer tank (assuming there is one) but not around the radiators.  The buffer tank heats up quickly, the return water comes back at the same temperature as the leaving water and a thermal cut-out is triggered.    Anything preventing water flow around the central heating system might do this, a blocked filter or otherwise.

The unit should not be working flat-out in mild conditions but if the indoor temperature is lower than you want it to be then it should definitely be working.  

matelodave

Most heatpumps (and a lot of boilers) have a flow switch which will cut off the pump if the flow is restricted or inadequate. Mine has stuck a couple of times in the twelve years I have a heat pump - mines a Daikin, so different to Ecodan but I'd guess theres a flow switch somewhere.

Fortunately mine is easy to diagnose as it come up with a fault code on the display if something goes wrong which indicates a restricted flow (which can actually be caused by all the TRV's shutting down or being closed when the thermostat calls for heat - the system should have a bypass valve to prevent this or at least one radiator without a TRV to maintain flow through the system).

In mine it's also pretty easy to take the flow switch out, clean it and put it back in (a new one is £135 plus the cost of a man to come to do the job, so I do it myself.).

The heating unit has isolating valves which allows me to just drain the unit and refill the unit, without having to drain the whole system. We also have the benefit of all plastic and copper pipework (no steel or ferrous radiators) so the water stays crystal clear, no crud or muck to clog heat exchangers

I'd guess that a fairly modern Ecodan has a pretty comprehensive monitoring system which would throw up error codes on the display if there was something wrong with it, although you may have to get into the engineering menu to find them - can you try downloading the installation and service manual for your machine to do some basic fault finding

Astria

matelodave said:

Most heatpumps (and a lot of boilers) have a flow switch which will cut off the pump if the flow is restricted or inadequate. Mine has stuck a couple of times in the twelve years I have a heat pump - mines a Daikin, so different to Ecodan but I'd guess theres a flow switch somewhere.

Fortunately mine is easy to diagnose as it come up with a fault code on the display if something goes wrong which indicates a restricted flow (which can actually be caused by all the TRV's shutting down or being closed when the thermostat calls for heat - the system should have a bypass valve to prevent this or at least one radiator without a TRV to maintain flow through the system).

When a neighbor had a heat pump fitted, they were told that the use of TRVs should be limited and only the bare minimum installed, possibly bedrooms only, the other rooms should have radiators appropriately sized for the heat loss in the room, balanced and then the system calibrating the water temperature based on weather compensation. This apparently maximizes the flow/return rate and generates the best COP. A buffer tank was installed instead for the 2 rarely used rooms they had on TRVs to maintain sufficient flow once those rads turned off.

Reed_Richards

My earlier point was that if you have a buffer tank then it may be possible for you to have perfectly good flow, as far as the heat pump is concerned, yet still have inadequate flow through the radiators.  Although the heat pump knows it has not got your house up to temperature, it thinks it has made the radiators as hot as it has been requested after five minutes and goes off, waiting for the radiators to cool down a bit.  It cannot tell that there is a blockage in the heating circuit beyond the buffer tank and so the radiators don't get warm at all.  At least that's my theory!  

UnicornGirl81

matelodave said:

Most heatpumps (and a lot of boilers) have a flow switch which will cut off the pump if the flow is restricted or inadequate. Mine has stuck a couple of times in the twelve years I have a heat pump - mines a Daikin, so different to Ecodan but I'd guess theres a flow switch somewhere.

Fortunately mine is easy to diagnose as it come up with a fault code on the display if something goes wrong which indicates a restricted flow (which can actually be caused by all the TRV's shutting down or being closed when the thermostat calls for heat - the system should have a bypass valve to prevent this or at least one radiator without a TRV to maintain flow through the system).

In mine it's also pretty easy to take the flow switch out, clean it and put it back in (a new one is £135 plus the cost of a man to come to do the job, so I do it myself.).

The heating unit has isolating valves which allows me to just drain the unit and refill the unit, without having to drain the whole system. We also have the benefit of all plastic and copper pipework (no steel or ferrous radiators) so the water stays crystal clear, no crud or muck to clog heat exchangers

I'd guess that a fairly modern Ecodan has a pretty comprehensive monitoring system which would throw up error codes on the display if there was something wrong with it, although you may have to get into the engineering menu to find them - can you try downloading the installation and service manual for your machine to do some basic fault finding

Yes it was throwing up error codes around 3 months back as I had issues with the water not heating up. Since then the heating hasn’t worked but there has been no error codes at all. 

I said from the start of this problem with the heating that something is preventing the hot water from reaching the radiators. Initially I had no underfloor heating and 3 of the 6 radiators upstairs got tepid to touch but not warm, the other 3 were stone cold. Then the whole lot stopped working. 

They decided it was a fault with both the pumps but clearly it isn’t. 

UnicornGirl81

Reed_Richards said:

My earlier point was that if you have a buffer tank then it may be possible for you to have perfectly good flow, as far as the heat pump is concerned, yet still have inadequate flow through the radiators.  Although the heat pump knows it has not got your house up to temperature, it thinks it has made the radiators as hot as it has been requested after five minutes and goes off, waiting for the radiators to cool down a bit.  It cannot tell that there is a blockage in the heating circuit beyond the buffer tank and so the radiators don't get warm at all.  At least that's my theory!  

That makes perfect sense really. 

Everything else seems to of been eliminated now so it’s got to be a blockage of some description