Altherma Problem

For the past couple of days my Altherma system hasn't been working properly at all. When I turn it on for space heating the backup heater kicks in straight and doesn't go off, thus the outdoor unit never gets going. I was speaking to the installer who said that this happens when the temperature in the underfloor system is low and the backup heater has to bring this up to 18 degrees before the outdoor unit kicks in. My problem is that it has been 2 days and the backup heater is still going - any suggestions??

If the circulating water is below 16C at switch on then the back up heater will energize to prevent liquid flood back at the compressor.

If the water circuit gets above 16c with the back up heater but the outdoor unit fails to kick in then I would suspect that you have a problem.

If the water circuit fails to get above the 16C mark with the back up heater you also have a problem.

You need an engineer to look at the fridge circuit.

minimise the amount of zones that you have open to reduce the amount of water being heated with the heater.
Then keep an eye on the flow temperature and the heat pump will start up.
get the flow up to 40 to 50 degrees and then open one loop at a time to keep the flow above 25 degrees.
with underfloor you should not be turning the system off if you can help it.
If you have an external thermostat connected and would like to turn the system off, don't! the best way to run this is all of the time using the 5 settings for the timer and adjust the flow temperature up and down in accordance to when you would like the system on.
When you would like the system off leave your thermostat to a set figure like 19 - 21 and set your flow temperature to 25 degrees.
This way you do not lose all of the heat out of your slab and your re heat time is quicker.

Thanks for this guys, managed to get it up and going again with your help. Another question for you though!! My water tepmerature at the indoor unit is up around 30 degrees but when I check the temp at the manifold it is down around 21-22 at the flow and around 19 at the return, should the temperature at the flow at the manifold be the same as the one at the indoor unit. The pipe coming into the indoor unit from the outdoor unit is always alot warmer than the one coming out to the manifold.

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Originally Posted by rebellad

Thanks for this guys, managed to get it up and going again with your help. Another question for you though!! My water tepmerature at the indoor unit is up around 30 degrees but when I check the temp at the manifold it is down around 21-22 at the flow and around 19 at the return, should the temperature at the flow at the manifold be the same as the one at the indoor unit. The pipe coming into the indoor unit from the outdoor unit is always alot warmer than the one coming out to the manifold.

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In relation to your findings of temperature drop,
* your pipework is either not insulated to the manifold and there are pipe losses.
Where do the flow and return to the manifold run?
* You have a mixing manifold installed on your underfloor, which is not required.
* you have a towel rail circuit piped in along the way which is creating short cycling of the flow.
*you have a pressure regulated by pass which is by passing prematurely.

Quote:

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Originally Posted by rebellad

Thanks for this guys, managed to get it up and going again with your help. Another question for you though!! My water tepmerature at the indoor unit is up around 30 degrees but when I check the temp at the manifold it is down around 21-22 at the flow and around 19 at the return, should the temperature at the flow at the manifold be the same as the one at the indoor unit. The pipe coming into the indoor unit from the outdoor unit is always alot warmer than the one coming out to the manifold.

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If you have a flow temperature of 30 and a return of 19 degrees you have a delta t of 11, this will mean that you have a reduced flow rate through the hydrobox.
Check the inlet strainer on the hydrobox as the system is designed to work with a delta t of 5 degrees.
Are you on high pump speed?