A discussion for the holiday - Struggling with recommendations for our OWN property!!

[Worcester]

We are on oil and are looking for our ideal solution - mains gas is in the street, £1500 to connect up (long drive..) We've got lots of spare PV output (on a sunny day) and an immersun unit -love it) We've got adequate area of land.

Maximum loft insulation, cavities filled on 1/4 of house, 3/4 of house solid walls, suspended wooden floors.

So our choices are:
Air Source Heat Pump
Condensing Gas Boiler
Ground Source Heat Pump with slinky coils (Not doing a borehole, way too expensive)
Thermodynamic Panels
Large Solar Thermal Array (we have the space) though poor angle of incidence
Log Burning Back Boiler
Biomass

We really don't want to redecorate the whole house as it's also got the small (not micro) bore piping to about half of the radiators.

So we really want a solution that can economically give us a high heat output for the exisitng radiators.

The high output Daikin and Panasonic ASHP's spring to mind, and possibly a large solar thermal array, however yesterday never got about -4°C here and today wont either.

At this instant 9:30am overcast, 13th December 2012 we are breaking even on generation / consumption of the PV

Now, seeing as we are struggling to come to a BEST solution, it gets difficult to recommend as the majority of our local domestic renewable energy marketplace will have similar challenges.

What are your thoughts...

 

[TedM]

Re: A discussion for the holiday - Struggling with recommendations for our OWN proper

Floor area? Current EPC score?

 

[Worcester]

Re: A discussion for the holiday - Struggling with recommendations for our OWN proper

Current EPC irrlevant (85 - B) due to massive PV! See Attached, anonymised (I hope)
Fllor Area, Ground Floor, 1400 sq ft First Floor, 600 sq ft (129 m2 + 54 m2)
View attachment EPC_Anon.pdf

 

[BruceB]

Re: A discussion for the holiday - Struggling with recommendations for our OWN proper

Connecting to gas is rarely wrong if available, rather like buying ibm 20 years ago.
With radiators, heatpumps are out really as your radiator system needs higher temperatures than they will economically provide.
I would investigate Biomass - it gives high temperature output and RHI is available.
If you have or can have a granny annex (ie x2 council taxes) then potentially commercial rhi is available now rather than waiting for domestic.

 

[dansk]

Re: A discussion for the holiday - Struggling with recommendations for our OWN proper

or electric UFH with all that pv ;-)

 

[MCS Renewables]

Re: A discussion for the holiday - Struggling with recommendations for our OWN proper

Danfoss DHP AQ heat pump with MIDI unit and buffer cylinder serving Smiths Eco rads.


Danfoss DHP-AQ
Ecovector® Low Level Fan Convectors - Smith's Environmental Products

with twin coil or hot water cylinder and a solar thermal system. (we use Barilla - Wholesale Solar Thermal Supplies Barilla Solar )

Done this combination recently on a house that had a gas supply which has now been removed.
Property has a 4kW solar PV system getting FITS and heat pump and solar thermal will qualify for RHI (if it ever happens!)

 

[Worcester]

Re: A discussion for the holiday - Struggling with recommendations for our OWN proper

It's the age old problem, we need the heat when we're not generating the leccy' I'm thinking that a big thermal store should be part of the solution.
Update we've got 16 existing radiators plus the towel rail.. (and a dual coil cylinder )

 

[jason121]

Re: A discussion for the holiday - Struggling with recommendations for our OWN proper

All three keeping existing radiators, my heat pump struggled last night on existing radiators still maintaining 21 degrees in house but shouild be 22

Large Solar Thermal Array (we have the space) though poor angle of incidence
Log Burning Back Boiler
Biomass
put them into one thermal store

 

[Worcester]

Re: A discussion for the holiday - Struggling with recommendations for our OWN proper

@jason121 - Well that sucks .........

And just started importing power, up to 200 Watts now ..

 

[Gavin A]

Re: A discussion for the holiday - Struggling with recommendations for our OWN proper

It's impossible to advise without knowing the heatloss rates.

If you've done a lot of insulation work since the rads were installed then it's possible the heat load has dropped sufficiently to allow the existing rads to be reused, but it'd need minimum cavity wall insulation, loft insulation and decent double glazing all round all round vs virtually none of this when the rads were installed.

 

[Worcester]

Re: A discussion for the holiday - Struggling with recommendations for our OWN proper

Most of the walls are solid wall (1939 bungalow originally) but then only 900 sq ft, so been extended, extended and gone up ...

So either lose 6 inches of every room dimension (Mrs wont like that ) and redecorate everywhere, then might as well replace the rads, i.e a complete refurb, (that's not likely to happen...) or EWI - even the EPC estimated £14k for that ....

This property is not unusual I could take you to 50 similar ones within 10 minutes drive... So they all have the same problem (and 75% of them are on oil as well)

 

[Gavin A]

Re: A discussion for the holiday - Struggling with recommendations for our OWN proper

Condensing Gas Boiler

or
Thermodynamic Panels or Large Solar Thermal Array (we have the space) for water heating in summer

plus
Log Burning Back Boiler
or
Biomass
for space heating in winter

the wood burner with back boiler option kinda depends on if you really want to had a heating system that has to be entirely manually fed or not, if not then some form of auto / batch feed biomass boiler plus decent sized thermal store / heating accumulator tank (1000l plus) to do 2-3 days heating at a burn.

I suppose if you really do have a lot of spare generation in winter then it could be worth considering an ASHP such as the panasonic that doesn't reduce it's output when the air temp goes down (increases power consumption instead), but you'd need to run it at 50+ so it'd not have a brilliant average COP. Again through you'd want a decent buffer tank so you only needed to run the heat pump in daylight hours (plus maybe economy 10 night time / afternoons?). No point if you'd just going to be using it as a straight boiler replacement as you'd be doing most of your heating when there was no solar PV generation.

 

[Worcester]

Re: A discussion for the holiday - Struggling with recommendations for our OWN proper

@GavinA, that's kind of what I've been thinking before I started the thread, I will then need a clever management system to optimise the use of the 'free' energy sources - solar thermal and PV so that the paid for ones don't kick in.

I know biomass is picking up big on the commercial scale, however what concerns me is that you are still buying fuel from a supplier, and based on curretn predictions we are going to be importing biomass.

One of my customers owns a biomass / wood pellet company, and they are seeing excellent growth

What I'm most likely to do is a Large Solar Thermal array with the log burning back boiler and large, at least 1000L thermal store, still thinking of backing it up with an ASHP of some sort though.... Daikin / Panasonic high output.

The next challenge will be the heat source management system to optimise the sources adn apply it to the heating as desribed above - any ideas?

Also if ECO can be used as part of the green deal, might use that to fund the EWI, as EWI unlikely to meet Golden Rule and then pay it off immediately, i.e. treat it as a grant... Need to see if we could qualify for that £1000 incentive too..

 

[The Solar King]

Re: A discussion for the holiday - Struggling with recommendations for our OWN proper

Cheapest solution today is a condensing gas boiler, conventional or system. Cost of gas supply and decent boiler (possibly one named after you) will knock spots off everything else.

A new condensing Gas bolier, solar thermal and new radiators took a large chunk out of our heating costs.

If you want to go the heat pump route, you will need to change your heat emitters for two reasons. Firstly to get the most out of the system. Secondly, it is possible that the domestic RHI may not be available to heat pump installations that do not achieve a minimum star rating for heat emitters greater than or equal to 3 star for ground source heat pumps and greater than or equal to 5 star for air source heat pumps, this being the level at which a CoP greater than 3.1 is estimated – the level at which the carbon emissions from a heat pump are lower than those from a gas boiler.

Having said all that, a major consideration is the acceleration of energy costs. We work on a projection of 7.5% per annum. This is based on DECC's own historic statistics over the last ten years. All fuel sources except on site generation will increase at the rate of the most expensive. You are not going to sell wood chips at a huge discount to gas electricity or oil, you are going to take a tidy profit thank you very much. This means the priority must be to reduce energy consumption as much as possible and still stay warm.

The approach taken in our own home (similar age and construction to yours) is to progressively improve the thermal performance of the building each time we renovate a room (second time round after 25 years of occupancy). This reduces disruption and starts making the cost bearable. We have UHF in a suspended floor in one room and will put it in another next year along with internal wall insulation. Every pipe in the place has been replaced and is heavily insulated.

If you have this kind of strategy, medium term possibilities open up. A thermal store with sufficient versatility to take heat from different sources will make more sense. As technological changes occur, you can alter the energy inputs to suit. Biomass does become a possibility. We are on the verge of storage for PV that could create a paradigm shift in the approach to household energy usage. Your big array could come in to its own.

The holy grail of renewables at a domestic level is cost effective space heating. Thermodynamics would not have created such a stir were this not the case. The RHI may improve the viability of heat pumps, but I wouldn't make a decision until the full details are known. In the longer term I would be putting my money on something solar and electric based.

 

[jason121]

Re: A discussion for the holiday - Struggling with recommendations for our OWN proper

The Solar King

When i have been selling heat pumps i do mention about the SPF 3.0 or above only achievable when changing Radiators. If i have been installing ASHP this year without changing radiators, would the installation still receive money from the RHI ??

 

[The Solar King]

Re: A discussion for the holiday - Struggling with recommendations for our OWN proper

The criteria for legacy system qualification has not yet been set for any technology. It is frustrating not to know all the qualification criteria for either this circumstance or for new installations across all technologies.

There is a degree of second guessing at the moment. Remember what the RHI is there to do is pay for renewable heat. That means criteria are likely to be quite strict.

 

[jason121]

Re: A discussion for the holiday - Struggling with recommendations for our OWN proper

Struggling with selling these not knowing to keep or change rads dependant upon RHI which is 7 months away

 

[Worcester]

Re: A discussion for the holiday - Struggling with recommendations for our OWN proper

@The Solar King
Thanks for the feedback, we've been here 18 years now and are just starting to plan the refurbs got 3 receptions, hall and kitchen to do over the next 12 -18 months so could put the UFH in those areas, by effectively rasing the floor levels, that would mean we could rip out the radiators on those areas too. (The main lounge is right at the end of the current system so performs the worst at the moment anyway)
A thermal store seems to be a definite MUST in all this minimum 1000L, maybe 2000L. We have only come across one other domestic site so far with 2000L store (2 x 1000L) and that was a large single storey barn conersion with UFH everywhere - anyone else got any experience of large stores?