Posted by: @makingtheleap

Hello all, I’m Nick and I’ve been reading through all of the good stuff on these forums.

We’ve just moved in to our new home and are immediately embarking on a journey shall we say.

The house itself was built in 1989 and is a detached 5 bed at around 2,900 square feet.

We knew when we bought it we would need to consider what we did from a heating and water perspective. Whilst the house does have gas, the gas is only used for the rangemaster in the kitchen and has never been kitted out for anything else.

The existing heating and hot water system consists of a huge Nightstor 160 dry core electric boiler and 2 hot water tanks (with immersion) totalling 570L. There aren’t many around still who service and repair these and my word is it expensive to run. Although it’s on economy 7 it eats so much electricity it’s unreal. Our monthly bills are £350 with an annual cost of £4,000ish (that includes electricity for day to day outside of the system). Even during the summer this thing eats electricity, even when it’s on all the lowest settings and is only really heating the water. 

Our annual heat requirements are around 25,300 for space heating and 2,500 for water heating. 

That leads me to the here and now. We’ve somewhat plunged in to trying to figure out what our best options are going forwards.

At the moment we are looking at getting Solar Panels and an Air source heat pump to replace the existing system.

We had an independent hear loss assessment done and have been working with a reputable company (no hard sell and given us so much information when asked, good and bad).

Where we have landed is potentially installing a 14Kw Stiebel Eltron, complete with EasyTron wireless TRVs and brand new radiators where needed (16 radiators in the house in total). Our pipe work is all 15mm pipes and would be flushed properly beforehand.

In addition to this, we are looking to install a 12Kw Solar PV system with a diverter which will divert any unused electric to the hot water, then anything left after that goes to the grid. We are lucky in that we have a 3 phase electric supply so can have as many panels as we want. Longer term we will assess the viability for adjustments as the company we are working with will track this with us.

We are currently in the process of replacing all the windows etc for new uPVC double glazing (existing is timber framed and draughty), increasing the loft insulation to 400mm and replacing all cladding/soffits/ drainage from rotting wood to uPVC. Thankfully the house already has good quality cavity wall insulation.

Do I know whether this is the right thing to do? Nope - feeling a little out of our depth here (although a friend who fits ASHPs thinks it’s good)

Do I know if it will save us money to justify the outlay? I think so

Will there be a return on the investment? Eventually

But what I do know is, we don’t want to stay with this monstrosity we have right now and we don’t want to go to gas given where that is heading and our desire to be green etc.

I’d be interested to hear what people think or want to know. 

Cheers

Nick

Hi Nick,

Welcome to the forum.

As I try to convince anyone who will listen, the starting point should be to improve your insulation, and before you ask, I am not writing this from the M25 or a police station. By reducing the heat demand, the system can be smaller, operate more efficiently, and cost less to install and operate.

Initially, from a cost perspective, I would have suggested installing a gas combi boiler, which would no doubt be much cheaper to fit, would probably operate with your existing radiators, and be cheaper to run on the present tariffs for gas and electricity.

If you are determined not to have a gas boiler, then a heat pump would be the next best option. If you can afford the additional cost, have the room, and are happy with the disruption, then a ground source heat pump would be the most efficient to install. An ASHP, though cheaper and easier to install, is less efficient and hence costs more to run than a GSHP.

I am pleased to see that you are having a solar PV system installed, which will help to power your ASHP along with providing much of your hot water throughout the year.

The heating requirements that you quote, are these calculated on your present heat loss, or the estimated heat loss after the present improvements have been completed?

Will your ASHP and solar PV be single phase or 3 phase?

I would suggest that you get quotes from other installers, and ask for details of the anticipated operating efficiency, and how the control system will work to keep the water flow temperature at the lowest temperature consistent with normal operation. Obvious, along with all the other questions relating to cost, reliability, warranties and performance guarantees, servicing requirements and spare parts availability.

I hope that this helps, but please fell free to ask any further questions.

@makingtheleap Nick,

I came from similar situation as you.  I live in a 1990 house that had storage heaters and an electric Aga (that was our monstrosity). It's a bit smaller than yours at about 1750 sq feet.  It cost a lot to heat and the Aga was close to £100 a month on its own.  Our house also had timber windows (now replaced) and we also put in another 200mm of loft insulation. The walls are quite well insulated already. We also have a 3 phase electricity supply. Our heat/HW requirements were about 22000/3000.

To cut a long story short, the Aga and storage heaters are gone and we have a ASHP system with radiators, run by a 14kW Ecodan.  We have applied for and got RHI.  The system seems to work well for both HW and heating, although we are yet to experience a full winter.  We've had a few cold days and nights though and it's been fine.  I'm also getting the optional MMSP monitoring although that's not in yet. 

With the RHI and lower running costs it will almost definitely pay financially compared to what we had.  It's also much, much better. We don't have the option of mains gas; if we had I probably would have gone down that route.  We have no PV yet, although thinking about it.

Any questions, just ask. 

And good luck!      

PS my story here

https://renewableheatinghub.co.uk/forums/renewable-heating-air-source-heap-pumps-ashps/my-ashp-installation/paged/1

@derek-m hi there and thanks for the info.

My first aim is definitely to improve the overall insulation. Increasing the loft insulation to 400mm, changing all of the doors and Windows and as we decorate, we will be adding insulation to the flooring.

The heat loss calc was done on both the existing with no changes other than adding the loft insulation, and based on if we do all the work (which we are), to ensure the system is designed appropriately. 

They have shared pretty much all the information with me and walked me through it so I’m comfortable it’s not been embellished.

We have really considered just going to gas, but just feel we want to move away from that. 

Saving money longer term is a driver but it’s for sure not the only or main driver for us.

I believe we will use the three phase for both but most certainly for the solar panels.

Thanks for the pointers on the questions, I’ll make sure to ask on the ones I haven’t already.

The scop value is 3.47 at 50 degrees. The Stiebel Eltron gear is all under a 7 year warranty, technical team is in Liverpool with support engineers throughout UK and parts are  pretty common.

Thanks

Nick

@kev-m Thanks for the reply! 

Your story is fascinating to read through, gives me confidence.

We had quotes from several places but they all came across as salesmen who when you asked questions didn’t have a clue. Until we met EPC-Improvements and Ryan, our heat loss man. It’s been a totally different experience with them and competitive pricing.

getting the solar panels is a big outlay but going to really support us, with supplying power to the heat pump, the house and the hot water. We are lucky given the size of system we can put in.

I know it’s a huge outlay (we are very money savvy and always have been) but unless the install etc goes horribly wrong, I can’t see how it won’t save us money long term alongside the RHI. Yes it’s not as cheap as gas (now) but I feel the benefits can and will outweigh the cons. 

Rooms will often only be at 18/19 degrees at best. Neither of us are particularly impacted by cold. The system will also have zone control for each room via the EasyTron which means for rooms we barely use we will maintain a lower temp.

We will also have a log burner in the lounge fireplace (can’t remember what type but it’ll provide additional heating in the lounge).

Fingers crossed. I will keep updating and responding to people on here!

@makingtheleap Hi Nick,

I think that you will be the first on the forum to have a 3 phase ASHP and solar PV system. I presume that you have a 3 phase supply because of the power demand of the Nightstor 160, that is to be replaced.

As an Engineer who has worked on 3 phase systems for most of my career, I would be interested to see how your system is to be arranged, particularly with regard to balancing the load on each phase. Obviously the standard 240v supply within your home will be derived from one of the phases to neutral. Since you have 2 hot water tanks with individual immersion heaters, it would be possible to supply them via power diverters from the other 2 phases, which would help to balance the load on each phase. I can provide details if you wish.