Pro's and cons of a heat pump

I've designed and fitted HP's. I'm an advocate for them. The one in my house is cheaper to run than the gas boiler we had in the previous house. Please note, it is the heating design that determines how good the HP is.

The outdoor units are all much of a muchness, the only real difference is the controls between different Makes. My personal favourites are Daikin, Grant and Nibe. Others will say Vallaint/Bosch etc. There isnt a great deal of diffence between any of them. Spares back up and usage of the controls are bigger factors for the homeowner. My own controls are never touched. They were set up when it was installed, I cannot recall touching them since to adjust anything.

I must stress, it is the heating design that makes or breaks the install. Octopus et al use a flow design temperature of 50 deg C. I would definitely design at 35 deg C. Each 1 deg rise in flow temperature uses 2.5% more energy to get that 1 degree. Hence a HP at 50 degrees uses 37% more energy than one that runs at 35 degreees.

I have been to many HP installs that are really badly designed and fitted. Sadly, Plumbers have been getting away with it for 40 years, in doing little design for their Installs. A gas boiler is usually oversized by a long way. Great, it heats the house up quickly, and will easily heat that house to 30 degrees internally, but, the cost to the homeowner is hidden - they arent aware that they are paying too much as their boiler is quite in-efficient for their use. The same mantra has happened with Heat Pumps, in that they just fit them, and think they will automatically just work. They wont, well, they may, but the running cost will be high. Get it designed properly, and it'll be a really good system.

Yes, you will need bigger radiators. Basically, the lower the flow temperature, the larger the heat emitters have to be. Typical new gas boilers (should) flow at 55 deg. A good HP will flow at 35 deg., so a radiator roughly twice the size will be required. This is all worked out from the house heat loss requirements. If a heat loss survey is done, the 'surveyor' should spend at least a hour in the property, possibly more, to get a good basis for the calculations for each room. Do not employ anyone who does not do a proper heat loss survey - it is the fundamental base to ensure you have a well designed system. Recently software has taken over, and they go round with a phone and record the house layout etc. The software then works out the heat loss. This is coming on, but, IMO, does not give as accurate  a figure as a proper survey. If it's within 10%, thats good, but why would you want to pay 10% more on your bills? Get it done right, and you'll be happy, with a well specified, efficient system.

Follow up if you have any more queries.

I've designed and fitted HP's. I'm an advocate for them. The one in my house is cheaper to run than the gas boiler we had in the previous house. Please note, it is the heating design that determines how good the HP is.

The outdoor units are all much of a muchness, the only real difference is the controls between different Makes. My personal favourites are Daikin, Grant and Nibe. Others will say Vallaint/Bosch etc. There isnt a great deal of diffence between any of them. Spares back up and usage of the controls are bigger factors for the homeowner. My own controls are never touched. They were set up when it was installed, I cannot recall touching them since to adjust anything.

I must stress, it is the heating design that makes or breaks the install. Octopus et al use a flow design temperature of 50 deg C. I would definitely design at 35 deg C. Each 1 deg rise in flow temperature uses 2.5% more energy to get that 1 degree. Hence a HP at 50 degrees uses 37% more energy than one that runs at 35 degreees.

I have been to many HP installs that are really badly designed and fitted. Sadly, Plumbers have been getting away with it for 40 years, in doing little design for their Installs. A gas boiler is usually oversized by a long way. Great, it heats the house up quickly, and will easily heat that house to 30 degrees internally, but, the cost to the homeowner is hidden - they arent aware that they are paying too much as their boiler is quite in-efficient for their use. The same mantra has happened with Heat Pumps, in that they just fit them, and think they will automatically just work. They wont, well, they may, but the running cost will be high. Get it designed properly, and it'll be a really good system.

Yes, you will need bigger radiators. Basically, the lower the flow temperature, the larger the heat emitters have to be. Typical new gas boilers (should) flow at 55 deg. A good HP will flow at 35 deg., so a radiator roughly twice the size will be required. This is all worked out from the house heat loss requirements. If a heat loss survey is done, the 'surveyor' should spend at least a hour in the property, possibly more, to get a good basis for the calculations for each room. Do not employ anyone who does not do a proper heat loss survey - it is the fundamental base to ensure you have a well designed system. Recently software has taken over, and they go round with a phone and record the house layout etc. The software then works out the heat loss. This is coming on, but, IMO, does not give as accurate  a figure as a proper survey. If it's within 10%, thats good, but why would you want to pay 10% more on your bills? Get it done right, and you'll be happy, with a well specified, efficient system.

Follow up if you have any more queries.