Leave heat pump on or switch on as required (weekends)

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timmmay

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#816417 12-May-2013 21:02

Some heat pumps run a cooling cycle followed by a heating cycle, so dehumidifying doesn't change the room temperature too much.

Skolink

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#816443 12-May-2013 22:00

timmmay: Some heat pumps run a cooling cycle followed by a heating cycle, so dehumidifying doesn't change the room temperature too much.

All heat pumps work this way. It is a gross waste of energy. I have never seen a heat pump with the indoor unit split so as one half works as a condenser and the other half as an evaporator simultaneously (as for a real dehumidifier).

As for your original question, I'll try to come up with some calculations tomorrow. My workmate is an expert on such things.

Handle9

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#816460 12-May-2013 22:47

Niel:
Handle9: Also FYI Niel reverse cycle refers to the reverse cycle of refrigerant - i.e. The forward cycle of refrigerant is in cooling, the reverse cycle is heating. There is a reversing valve in the refrigerant circuit which provides this functionality.

"Reverse cycles" plural as in all the cycles. Unless you have an old system, an aircon can be set to heating only, cooling only, dehumidify, or automatically reversing cycles between heating and cooling as needed. The issue is that after cooling there is condensation on the element so when it reverse to heating you get a faint metallic smell.

When you talk about air conditioning reverse cycle has a very specific meaning referring to the operation of a reversing valve. One of the other names for a heat pump is a reverse cycle air conditioner. What you are referring to is mode control. What you are calling reverse cycles is called automatic changeover. You should avoid it any way as it's difficult to get good control in a domestic situation as often the indoor units are put in crappy locations and they only sense temperature where they are mounted. The worst possible result is hunting from heating to cooling and back again, particularly with oversized units. It's very inefficient to do this.

kiwitrc

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#816475 13-May-2013 05:30

Consumer have just released a free heating guide here which might be of interest to some.

Wade

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#816682 13-May-2013 12:57

We've got a heat pump and an hrv system and I have to say as a combo these two units work in very well together and keep the whole house at a very even temperature

Skolink

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#816720 13-May-2013 13:21

Wade: We've got a heat pump and an hrv system and I have to say as a combo these two units work in very well together and keep the whole house at a very even temperature

Is that a true heat recovery ventillation system or an HRV brand system, two different things?

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Wade

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#816922 13-May-2013 18:17

Skolink:
Wade: We've got a heat pump and an hrv system and I have to say as a combo these two units work in very well together and keep the whole house at a very even temperature

Is that a true heat recovery ventillation system or an HRV brand system, two different things?

It is just the simple positive pressure HRV branded system. The two work completely independent of each other but effectively the HRV keeps the temp relatively stable (within its limits) meaning the heat pump never has much of a job heating or cooling the air to desired setting

timmmay

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#816936 13-May-2013 18:32

All the HRV does it pump air from the ceiling to the house. It's good for clearing out stale or moist air, but it's working against the heat pump on cold nights. I have mine on a timer so it only goes during the day, but if I have more people at my place I might have it run for part of the evening too.

ajobbins

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#816937 13-May-2013 18:33

Wet air is MUCH harder to heat or cool than dry air, which is why the combination of an HRV type system with a heat pump is a very good combo.

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timmmay

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#816988 13-May-2013 19:37

I thought that was what I said. That's why I run it during the day, to push all the moist air from sleeping and cooking out. If you run it at night when it's cold it does get rid of some moisture, but at the expense of making it cold. I have good moisture removal from the wet areas and only two people in a big house so it doesn't matter that I don't run it at night. If it did start to feel moist I'd just have the timer turn it on for ten minutes an hour or something.

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