Heat pump tariff / prepayment meter

chlyou4421

I had a heat pump installed by my landlord where it is now costing me almost £200 a month with Scottish Power.  My house is set to 16 degrees, I’m in a small 2 bed house with my daughter and we are out most of the time. I have tried to switch to Octopus today where I was told I failed the credit check and would have to pay £150 upfront. Does anyone have experience of heat pumps and prepayment meters? Am I able to switch if I have bad credit? I don’t feel I was a suitable candidate for the heat pump but they put it in anyway. 

matelodave

What sort of heating did you have before and how many kwh a year did it use - you really need to understand your consumption in kwh rather than just £££ to get any meaningful comparison. How much did you pay before?

There are lots of questions that need to be asked about your system and how you operate it. TBH £200 a month doesn't sound excessive over the winter as its likely to drop significantly now the warmer weather is coming.

What make and model heatpump have you got, did you have your radiators replaced with bigger ones (assuming that you had rads before)

What sort of controls have you got. How big is your hot water tank and how hot do you keep the water and how often do you heat the water.

chlyou4421

I had gas radiators before. I’m not sure of my usage as didn’t have smart meter back then, but was paying around £140 a month for both gas and electric. I have a daikin Altherma 3m (?) and is 210L. Yes all radiators were replaced for larger ones. This is where my problems come in as for settings. It is set at around 50degrees, and have it set to maintain that temperature all day. I just previously had it set to heat up between 5-9 but was just inconvenient and the cost difference wasn’t much. 

matelodave

I'd be inclined to reduce it to 40 degrees and see how that goes or even set the weather compensation. Generally most heatpump installations are left on default settings but a decent installer should adjust and balance the system. However to get the best out of a heatpump you need to understand how it works and how to tweak it to suit your requirements

However now that spring is sprung and the weather is getting warmer you'll find that power consumption will fall anyway and you'll find its hard to set it up against situations when its very cold until next winter.

NedS

Yes, reduce your flow temperatures. Heat pumps are massively more efficient at low flow temperatures. Set it as low as you can, whilst still keeping the property warm enough. How low you can go will depend largely on how big your radiators are. We ran ours at 32C for most of the winter and it worked out much cheaper than the cost of gas.

As most of the heating season is over now, you will not likely get a chance to really tune the system until next winter. Use the time between now and then to learn about heat pumps and their operation. You may be able to significantly reduce your bills next winter.

The next task is to ensure you are paying as little as possible for electricity as you are now using a lot more of it. I have no idea of the costs of pre-pay meters, but I imagine they are not cheap. Normally having a smart meter and paying in advance through direct debit is the cheapest method, but again this is something you can investigate.

chlyou4421

NedS said:

Yes, reduce your flow temperatures. Heat pumps are massively more efficient at low flow temperatures. Set it as low as you can, whilst still keeping the property warm enough. How low you can go will depend largely on how big your radiators are. We ran ours at 32C for most of the winter and it worked out much cheaper than the cost of gas.

As most of the heating season is over now, you will not likely get a chance to really tune the system until next winter. Use the time between now and then to learn about heat pumps and their operation. You may be able to significantly reduce your bills next winter.

The next task is to ensure you are paying as little as possible for electricity as you are now using a lot more of it. I have no idea of the costs of pre-pay meters, but I imagine they are not cheap. Normally having a smart meter and paying in advance through direct debit is the cheapest method, but again this is something you can investigate.

By running it at 32 does that not make your bath water luke warm? I wanted to be able to keep a roasting hot bath!

Reed_Richards

chlyou4421 said:

By running it at 32 does that not make your bath water luke warm? I wanted to be able to keep a roasting hot bath!

You can set completely different temperatures for your heating and your hot water.  A hot water cylinder heated with 32 C water would indeed remain lukewarm but you should be able to heat your hot water cylinder to 45 C or more.  Most people would find 45 C water uncomfortably hot.  

Spoonie_Turtle

chlyou4421 said:

NedS said:

Yes, reduce your flow temperatures. Heat pumps are massively more efficient at low flow temperatures. Set it as low as you can, whilst still keeping the property warm enough. How low you can go will depend largely on how big your radiators are. We ran ours at 32C for most of the winter and it worked out much cheaper than the cost of gas.

As most of the heating season is over now, you will not likely get a chance to really tune the system until next winter. Use the time between now and then to learn about heat pumps and their operation. You may be able to significantly reduce your bills next winter.

The next task is to ensure you are paying as little as possible for electricity as you are now using a lot more of it. I have no idea of the costs of pre-pay meters, but I imagine they are not cheap. Normally having a smart meter and paying in advance through direct debit is the cheapest method, but again this is something you can investigate.

By running it at 32 does that not make your bath water luke warm? I wanted to be able to keep a roasting hot bath!

Per the above post, keep a hotter hot water - but if that's then not quite hot enough for your bath whilst being hot enough for everything else, might just be cheaper to top the bath up with a kettle

matelodave

As said above you can control your heating and hot water separately so learn how to drive your controller, get your heating temp as low as you can whilst still being comfortable and reduce your hot water temp to around 45 degrees.

Also sort out your timings, are you keeping your hot water tank hot all day, even when you are out or over night - try just heating for an hour or so before your bathtime and then see how long your hot water lasts.
If necessary give it another boost if it runs out (or try to use less hot water so it doesn't)


Looking at the specs for a specific ECODAN heatpump at 2 degrees outside has a  COP of 3.44 at 2  with a flow temp 35 degrees by winding it up to  45 the COP reduces to 2.75 and 50 degrees it drops to 2.3

That sthe equivalent of paying around 7.25p/kwh at 35 degrees, 9p/kw at 45 degrees or 10.87p/kwh to get it up to 50 degrees. If you can reduce your heating temps and put up with cooler water in your bath you can save yourself a lot of money

These figures get worse when its everso cold (below freezing outside) and significantly better when the temp is around 7 degrees.

Heatpumps work most efficiently and cost less to run when run low and slow to maintain a temperature, rather than on/off like a gas boiler as they have to work much harder everytime they turn on to restore the temperature.

chlyou4421

Reed_Richards said:

chlyou4421 said:

By running it at 32 does that not make your bath water luke warm? I wanted to be able to keep a roasting hot bath!

You can set completely different temperatures for your heating and your hot water.  A hot water cylinder heated with 32 C water would indeed remain lukewarm but you should be able to heat your hot water cylinder to 45 C or more.  Most people would find 45 C water uncomfortably hot.  

I have no idea how to do this unfortunately. When I dropped to around 40 degrees the bath was not hot enough (I like to be roasting in the bath)

QrizB

chlyou4421 said:

I have no idea how to do this unfortunately. When I dropped to around 40 degrees the bath was not hot enough (I like to be roasting in the bath)

If you can tell us the make and model of heat pump, we can probably give you some help with finding the settings.