Andy T

This is incredibly helpful and again I'm really am grateful. I had a quite chat with the installer today (as they are ordering the equipment) and have agreed to speak again to discuss installation. I'm going to print all of this out and study it over the weekend to hopefully give me a full understanding of what I'm trying to achieve and agree with him. Again, I'm so grateful for the time everyone for the time and advice that's been given here.

Okay. Thanks JohnMo.

Thank you. Good idea. I will ask for a diagram

I can see on the quote it states "we have allowed for all associated pipework for the connection and fitting of the Grant external unit and cylinder valves, pumps and volumizer/buffer tank". It is to supply and fit a Grant Aerona 3 Air source heat components: 1 No. 10kw R32 Inverter Driven HPID10R32 unit 1 No. installations pack A (HPIDR32PACKA) 1 No. UK Elite High performance 250L cylinder 1 No. Grant Mag 1 filter

I take your point re the window replacement. The house was built in 2000 and generally seems good, but the windows installed were softwood (perhaps a lack of money towards the end of the build?), were not maintained in any way and therefore rotted, hence total replacement required. I have the heat loss report here in front of me but I'm honestly not sure how to answer the question re the flow tempts needed in the UFH - I'll try and make sense of this. We are in fact pretty exposed in a semi-rural area - we are at the top of a small hill with fields all around us. The house takes a pretty good battering on windy days! Yes, I wondered if the Homely would be unnecessary for us - we are not looking for something particularly finely tuned after happily surviving on the oil fueled underfloor heating.

Thank you very much for this information. I won't pretend, it does all get quite confusing. It's not too late for us to change to a different unit/different make. I'm wondering whether to go ahead with the Grant or perhaps change to another. Alternatively I'm thinking of asking the installer in advance how they intend to install the unit as this seems to be a large part of whether the unit will be efficient or not....

Thanks for this Garald. So reassuring to hear we've made a good size choice as I understand it's more complicated than it may initially appear (bigger isn't necessarily better) and was very worried about getting it wrong. Also pleased that people seem to be aware of Grants as Valliant seemed the obvious choice at first. Also, we're advised that Grants are quick to respond if things go wrong so I'm hoping this is the case. Yes, as you say, I was worried about how the pump would cope working at half steam as well as full steam so the plan was hopefully to have a safety margin. Once again thank you, as feeling very reassured and thankful for this site.

That looks really useful - I've just read about it on the Grants site. I'll definitely look into the Homely system and check with our supplier if we can use this with our pump. Thank you.

Thank you Andehh

Many thanks for this JohnMo. That's really helpful and we've gone ahead and ordered the 10W Grants which will be installed mid-February. Many thanks for this re-assurance Thank you also Marvin for confirming. So grateful for all the help from this site Apologies for the late response, but I've only just seen your two posts for some strange reason.

Yes Tom, it will be doing the hot water too.

Thank you so much for both replies. I think we've decided to get another heat loss report just to make sure.

We’re looking for some advice on size of air source heat pump to install if anyone can help please. We have a detached chalet style bungalow, with solid (concrete) floors and with an underfloor wet heating system, currently run on Kerosene oil. The property was built in 2000 and as far as we’re aware has standard type insultation in the walls and loft (we can’t ascertain exactly what we have) and we’ve recently installed double glazing. We’ve done quite a lot of homework and had two companies round to look at our house and quote and had a heat loss survey carried out, demonstrating a total heat loss of 6,688E (43 w/m2). The house is approximately 160m2 . One company recommended a Valliant 7kw Thermo Plus heat pump. The other company (prior to seeing the hot loss report) recommended a Grants 13kW R32 heat pump. On sight of the heat loss report, the second company recommended a Grants 10kw R32 heat pump. We see buying a larger heat pump does not cost much more, but are concerned if we install larger than needed then this may cost more to run and/or not run efficiently. Any help or advice would be really appreciated. Our boiler will probably not last much longer as it’s on its last legs so are keen to get on with this project.