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Air Sourced Heat Pump.

Zoomup
A person today that I was talking to, that has had a new build home which was required by building regs. to have an air sourced heat pump for heating and hot water, complained that the system was slow to heat or cool as required. He said that he had to have underfloor heating installed. It was slow to warm the rooms on cold days. He recently had the system set to cool the rooms on the very hot recent days. But this morning was cooler and he required heating. Is this normal?


Z.
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    davezawadi (David Stone):

    ... or that the radiator mainly transfers heat by convection or a myriad of other things.


    If radiators really were radiators, we'd paint them black, not white. We'd also not have low surface temperature ones for care homes, etc.


    This thread reminds me of lessons in the third form when we considered whether it was cheaper to heat hot water intermittently or constantly - not much lagging on tanks in those days! Also the difference between heat and temperature.


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    The European Social fund paid for me to do a training course organised by Coventry University that explained the proposed Building Regulations requirements and building to Passivhaus standards, as well as actually doing a building air tightness test with a blower door, you are not even on  the same wavelength.


    Regards windows the expectation is that they will be sealed and triple glazed with E-glass with heat recovery ventilation systems.


    Regards radiators, they can be the size of the floor.


    And so on and so forth, you have the wrong mindset.
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    If you're designing a building from scratch, why not use warm air heating ducts?  Saves all the plumbing, and the system can run at a lower temperature.
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    My dad and his business partner built houses on spec back in the 1960’s with both electric and oil fired warm air heating, back then it was a big selling point, but fell out of favour over forty years ago. Most housing associations replaced the warm air heating with electric storage heaters and created a cupboard where the warm sir unit used to be..


    It does need a heat source with a big output or a big heat store.
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    The best feature of wet UFH is that it’s just pipework in the floor and the actual heating appliance can easily be swapped if there’s an issue.
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    Simon Barker:

    If you're designing a building from scratch, why not use warm air heating ducts?  Saves all the plumbing, and the system can run at a lower temperature.


    I owned a house once that had warm air heating It was built in the70s and had a gas "boiler". Hot water was stored in a conventional vented copper cylinder. A fan blew the warm air around the house. The system was very fast in raising room temperatures if you came in from the cold in the winter chilled through. The only real minor drawbacks were:

    1. The system was very good at blowing dust about the house.


    2. It was slightly noisy in operation due to the fan and moving air.


    Its good points were its efficiency and speed of operation. The boiler could also be controlled by an old fashioned time switch built into the from of the boiler casing for automatic control.


    Z.


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    Sparkingchip:

    The best feature of wet UFH is that it’s just pipework in the floor and the actual heating appliance can easily be swapped if there’s an issue.


    The worst feature about pipes in the floor is that if they block or leak it is invasive and costly to repair the system, as I have seen first hand.


    Z.


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    No, Andy, I do not have the wrong mindset. Yes, you can do all these things, and run the heating 24 hours a day and all the rest WITH A NEW BUILD. We have 30 million or so "old build" properties to manage, and none of your ideas are practical or affordable. Even the cost of running say 3kW 24/7 would bankrupt many people and the electricity system COULD NOT DELIVER IT. Have you ever tried to retrofit concrete floors in a 30s semi, or an older block of flats? Underfloor heating must run 24/7 to be much use due to "the time constant" I mentioned in my design piece. Getting a reasonably sized building to 3kW of loss is very difficult, try the calculation yourself, I was involved in a building (actually a Church hall) built like this idea, it cost £2.2 Million, and costs a considerable amount in energy despite having a lot of PV (10kW) solar collectors for hot water, and tons of insulation. It also has 50kW of gas boilers for when the weather is "inclement", and more still for hot water. Because it has underfloor heating it must be run 24/7, It costs a small fortune to run, although the Electricity bills are usually slightly negative. The gas and maintenance bills are not small, but it "green" and Energy class A. Its floor area is not much more than a number of large houses (Victorian) nearby. The heating and ventilation control systems still do not work correctly 4 years later, and the heating, etc "Consultant" has ceased trading to prevent bankruptcy. The only part to budget and works properly is my design!
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    "no one wants any bad news, and I am ignored completely. This is the typical client!"

    Aint that the way of the world Dave lad?

    In every way in every discipline of the human mind we will always hit that one.

    Hence our motto thru the ages - We the unwilling!


    We the unwilling, attempt the impossible for the ungrateful.

    We have done so much, with so little, for so long

    that we are now qualified to do anything with nothing.


    A quote from years ago and still holds true today!
  • 0
    Zoomup:

    A person today that I was talking to, that has had a new build home which was required by building regs. to have an air sourced heat pump for heating and hot water, complained that the system was slow to heat or cool as required. He said that he had to have underfloor heating installed. It was slow to warm the rooms on cold days. He recently had the system set to cool the rooms on the very hot recent days. But this morning was cooler and he required heating. Is this normal?


    Z.




    Lets go back to the original post:



    • It is a new build home, therefore it should have all the required insulation.

    • The user complained it is slow to respond, that suggests a lack of understanding of how to operate the system.

    • The user has an issue because the system was set to chill the floor, but then wanted heating instead, so presumably it took at least twice as long to heat up, which is not a fault with the system unless there are external weather sensors to determine the outdoor temperature so that it can optimise the system to reach the desired room temperature at specific times.


    All in all it suggests user error or a lack of understanding as to how the system operates, assuming of course that a decent control system was installed in the first place. It is not a fast reacting system, it needs time to run and it should not be turned off, the temperature should merely be adjusted throughout the day, so the system is simply raising the temperature rather than heating from cold, bearing in mind that if the home is well insulated the heat losses will be low.

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