Octopus Heat Pumps

Reed_Richards

With many Hive equivalents, like the Drayton Wiser I use, you can either limit the number of starts per hour or tell the controller what sort of heat source it is controlling (which will have the same effect). So if my heat pump goes off then my controller won't try to start it again until 20 minutes after the last time it was started.  This prevents short cycling.  But I cannot see that the Hive has any setting that would allow you to do this.  And the fact that you get 2 minute cycles would imply that the Hive makes no effort to control short cycling.  That's strange, because it's quite possibly more harmful for a gas boiler than for a heat pump.    

matt_drummer

Reed_Richards said:

With many Hive equivalents, like the Drayton Wiser I use, you can either limit the number of starts per hour or tell the controller what sort of heat source it is controlling (which will have the same effect). So if my heat pump goes off then my controller won't try to start it again until 20 minutes after the last time it was started.  This prevents short cycling.  But I cannot see that the Hive has any setting that would allow you to do this.  And the fact that you get 2 minute cycles would imply that the Hive makes no effort to control short cycling.  That's strange, because it's quite possibly more harmful for a gas boiler than for a heat pump.    

These `controllers' may limit the number of starts per hour but they don't actually prevent short cycles do they?

It is still possible for the compressor to start and only run for very short periods I assume?

Reed_Richards

matt_drummer said:

These `controllers' may limit the number of starts per hour but they don't actually prevent short cycles do they?

It is still possible for the compressor to start and only run for very short periods I assume?

Yes that's entirely true but highly unlikely. 

If the compressor starts, runs for two minutes then goes off then it almost certainly hasn't supplied any significant amount of heat.  Since the duty cycle is 2 minutes every 20 minutes that's very unlikely to be sufficient to maintain a stable temperature.  So the room/house will get colder and colder and so will the temperature of the water being circulated by the heat pump.  What will then happen is that the system will settle down to a longer duty cycle; whatever is necessary to maintain a stable temperature. 

The only circumstance I can think of where that might not happen is if the heat pump is greatly over-powered, weather compensation is turned off and the Leaving Water Temperature is set somewhere near the maximum that the heat pump is capable of supplying.      

Spies

I have a permanent live and then switched live to the boiler where my thermostat lives, is that likely to work ok with the madoka?

Alnat1

Previously gave up and cancelled installation when our local Environmental Health were unwilling to grant planning permission because sound was 2db over recommendations.

Found out a decibel correction of -10 can be applied to the calculation if there is a wall/fence blocking sight of the "assessment position" of neighbours bedroom window. This would bring sound level to within permitted development but would need to be 4m high at the boundary, not possible. 

Last week I had a light bulb moment. A 3m x 2.4m lean to pergola over the area where the heat pump would be placed, with a 40cm wide louvre panel down the side against the house wall which appears to block the view of the window. Might need another panel across the top, hard to work out all the angles until it's up.

Had a chat with Octopus and they think this could work. In fact, the guy I chatted to said maybe this could work for lots of others in the same situation. So back to the beginning, another survey booked and it all starts again.

Quote has gone up £600 since last time, maybe I can ask for a discount for coming up with a solution?

wrf12345

"This would bring sound level to within permitted development but would need to be 4m high at the boundary, not possible. "

That sums up council rules nicely, yes you can have it if you have a fence but you can't have a fence because it is too high...

Alnat1

wrf12345 said:

"This would bring sound level to within permitted development but would need to be 4m high at the boundary, not possible. "

That sums up council rules nicely, yes you can have it if you have a fence but you can't have a fence because it is too high...

Exactly, although the rules are from the government, the local council planning department are supposed to follow them. I still can't get over the fact that if our neighbour can't see the heat pump, it then doesn't matter if he can hear it.

Alnat1

Thought I'd update and let you know that I had a new survey yesterday and the pergola with louvre side panel has allowed the heat pump install fall within permitted development.

I signed the contract around lunchtime today. Had to agree to remove the top bars of the pergola before the install team turn up, so they can get their ladder up, not a problem.

Spies

Good news... 

In addition to double the funds available for BUS grant (as in the pot not the amount you get)... 

The government will also remove a rule which had meant heat pumps, which are installed outside, would need to be at least 1 metre away from a property boundary.

Reed_Richards

That is good news.  Can you cite the source of your information, @Spies?