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Author Topic: Huge building heating help  (Read 6678 times)
guydewdney
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« on: February 25, 2017, 08:15:50 PM »

We've bought a massive house.... it's 15,000 sq ft or 1,500sq m. 15 bedrooms, 14 bathrooms, 7 receptions.

No gas

Minimal insulation

Commercial building.

Listed, grade II. Listed in September 2016

Heating bills are staggering, as you can imagine. 1/4 of the house has wet central heating, we are increasing it to about 1/3rd. The rest is electric heating. We are replacing the electric convector heaters with oil filled wifi smart radiators. It's not financially viable to put wet heating throughout.

Rhi for wood chip provides about 3p per unit. Wood costs 5p a unit. So new fuel will cost 2p a unit not 6p which is what we pay for heating oil. So a saving of 4p a unit. We used about 1000 litres in the last month, month and a half. Or 10,000kwh in that time. That's 400 quid saving. A month.....

How would the figures work with ashp?

Is there another solution we should consider? Solar PV isn't possible, as all we can have is 3kw per phase, which is pointless on this scale
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desperate
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« Reply #1 on: February 25, 2017, 09:03:18 PM »

Grade 2 listed with no insulation or gas, blimey you're brave and incontinent going by the amount of bathrooms. If you can deal with the listed status you have to go big with the insulation or the heating bills will bankrupt you whatever you install, guess you know that already. Individual ashp units can be had for not a lot of money and as a quick and dirty fix might suit. How much of it are you planning to heat and to what sort of temp? Solar gain could be usefull, you must have at least a few south facing windows.

Desp
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guydewdney
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« Reply #2 on: February 25, 2017, 10:03:08 PM »

Listed building officer suggested pellet boiler....

Lots of bathrooms due to business plan, which is whole house let, i.e. Almost a hotel, so ensuite is expected.
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ringi
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« Reply #3 on: February 25, 2017, 10:22:00 PM »

How much do you need to heat it when it is not rented to customers?    (I assuming the rent per night is VERY high, so will cover heating while rented.)

Does the listing allow internal wall insulation?

I assuming you can't change the external in any way.

Do you have land to grow wood as part of the property?

Do you have large barns etc that could be used to season wood before it was chipped?

Will there be a member of staff on side that could load a log boiler
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rogeriko
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« Reply #4 on: February 25, 2017, 11:02:43 PM »

We just installed 3 Froling pellet boilers in a house of that size + 12 smaller cottages. Same story, main house is for rent daily. They used to use 400 litres of oil per day, now they collect the RHI check instead. You need a boiler over 200kw in order to get 5.24p per kw for 20 years.
« Last Edit: February 25, 2017, 11:18:39 PM by rogeriko » Logged

dhaslam
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« Reply #5 on: February 26, 2017, 12:30:30 AM »

Seems like pellet boilers is about the only  way.    Bulk pellets should cost about 20p per kilo and produce a most 5kWh.  You get a much more regular burn with pellets compared to woodstoves as well as less emissions.   Almost no work as well.   
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phoooby
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« Reply #6 on: February 26, 2017, 02:42:46 AM »

Any idea on the gas connection cost ?
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Tombo
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« Reply #7 on: February 26, 2017, 05:46:56 AM »

Hi Guy,
          At the risk of suggesting you suck eggs... Beyond the usual mantra insulate insulate insulate .....The set point temps need to be carefully controlled.  Warm enough that people don't feel cold, but cool enough that they don't open the window to cool down. 
Typically you can save 10kWh per bedroom per day by getting it right.  Digital room stats with suitable programming & calibration  help. ie- it's 25  degrees in here, it must be me.

Things like the flow rates on the secondary returns often produce good savings too, with no loss of function or performance. Plumbers habitually set pumps to 11.

Sounds like a big project. Good luck.

 bike


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todthedog
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« Reply #8 on: February 26, 2017, 07:33:44 AM »

Blimey Guy you are a brave man!   I wish you well with your project and especially the planning.
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pdf27
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« Reply #9 on: February 26, 2017, 09:36:17 AM »

Some disjointed thoughts:
  • If you're stuck with existing insulation levels, then I think your proposed approach of only providing heat when required is a good one. Are you fitting wifi radiator valves to the wet system to match the electric radiators?
  • If possible I'd design the system to make extending the wet system as easy as possible in future years - because they aren't viable now doesn't mean that they won't be in future.
  • How much time and energy can you put into the system? Logs are likely to be cheaper than pellets but are a lot more work.
  • Do you have expected heat load calculations and predicted load factors/occupancy rates? If you're expecting to be mostly getting visitors in the summer then a big chunk of the demand will be for hot water for instance. If in winter then the emphasis shifts to heating and perceived cosiness - at which point several wood stoves in the common areas would be a very good bet, they'll be considered a nice feature, the visitors do most of the work and the heat is much cheaper than direct electricity.
  • Don't discount PV - the limit isn't 3kW per phase but 3kW of export per phase in virtually all cases. Given your predicted loads I can't help thinking that exporting too much will be the least of your problems - you have endless opportunities to divert power, even if it's just taking a bit of chill off otherwise empty rooms. Realistically you're going to have a big year-round demand for hot water which helps a lot here.
  • I've got my doubts about ASHP as a winter option, due to how big the system would have to be. As a summer system for mostly hot water it might be quite attractive though - much less work than biomass, you'd get great COP and time-shifting it to make use of PV is easy
  • Hot water use needs a lot of thought - with 15 bathrooms then shower water consumption (indeed water consumption in general) is a big issue. That means shower drainwater heat exchangers on every one is a big saving if at all possible: 50% energy saving and reduction in the amount of hot water you need to store. Same applies to low-flush toilets.

Lots of questions, but if I had to guess I'd say lots of PV with an export-limiting inverter, ASHP for spring/summer heating and hot water, biomass boiler for winter heating and probably a load of log stoves scattered wherever looks appropriate for ambience and supplementary heating.
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Bodidly
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« Reply #10 on: February 26, 2017, 09:48:47 AM »

You should be able to do logs for 4p per kWh if buying in a wagon load and paying for processing at around 12 per cube. Still a lot of work involved
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guydewdney
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« Reply #11 on: February 26, 2017, 10:59:54 AM »

Some disjointed thoughts:
  • If you're stuck with existing insulation levels, then I think your proposed approach of only providing heat when required is a good one. Are you fitting wifi radiator valves to the wet system to match the electric radiators?

Current plan is just to extend the wet ch to the rest of the front of the house, which is relatively easy. To size for the rest of the house requires a major pipe size or doubling up. Complex and expensive. I've not seen wifi rad valves.

  • If possible I'd design the system to make extending the wet system as easy as possible in future years - because they aren't viable now doesn't mean that they won't be in future.

As above

  • How much time and energy can you put into the system? Logs are likely to be cheaper than pellets but are a lot more work.

Nowhere to store the logs in the amount required. Staff are not to be seen during the customers stay, as much as possible.

  • Do you have expected heat load calculations and predicted load factors/occupancy rates? If you're expecting to be mostly getting visitors in the summer then a big chunk of the demand will be for hot water for instance. If in winter then the emphasis shifts to heating and perceived cosiness - at which point several wood stoves in the common areas would be a very good bet, they'll be considered a nice feature, the visitors do most of the work and the heat is much cheaper than direct electricity.

    Not viable to do dhw with the wet system, the runs are far too long.


  • Don't discount PV - the limit isn't 3kW per phase but 3kW of export per phase in virtually all cases. Given your predicted loads I can't help thinking that exporting too much will be the least of your problems - you have endless opportunities to divert power, even if it's just taking a bit of chill off otherwise empty rooms. Realistically you're going to have a big year-round demand for hot water which helps a lot here.

Nope, already had this conversation with my dno. It's 3kw or nothing.
  • I've got my doubts about ASHP as a winter option, due to how big the system would have to be. As a summer system for mostly hot water it might be quite attractive though - much less work than biomass, you'd get great COP and time-shifting it to make use of PV is easy
  • Hot water use needs a lot of thought - with 15 bathrooms then shower water consumption (indeed water consumption in general) is a big issue. That means shower drainwater heat exchangers on every one is a big saving if at all possible: 50% energy saving and reduction in the amount of hot water you need to store. Same applies to low-flush toilets.

Lots of questions, but if I had to guess I'd say lots of PV with an export-limiting inverter, ASHP for spring/summer heating and hot water, biomass boiler for winter heating and probably a load of log stoves scattered wherever looks appropriate for ambience and supplementary heating.
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biff
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« Reply #12 on: February 26, 2017, 11:48:15 AM »

Aye Guy,
         I would echo Tod,s sentiments. Your,s is indeed a massive undertaking,structure wise never mind the planning parameters ,which can depend on the mood of the heritage people.
 If you are going to be under their tight control,then you should apply for a financial grant as big as you can get after you have costed and done the books for the whole finished job,
14 bathrooms means that you are dealing with a commercial enterprise and my dalliance with medium sized commercial gasifying boilers left a very good impression on me. They are astonishingly economic
and can be loaded to burn for 24 hours non stop. they take 4ft lengths of logs, and all kinds of timbers..The down side is that the thermal stores are massive and the pipework is 3" +. One local to me here needed a shed that is 20ft square. then a shed for drying the timber but the economics make it very worth while.
 You know my views on Insulation..Insulate,, Insulate and insulate again. You just have to go and find out exactly how much you can improve the property and find out what you cannot do.
Bear in mind Bobby bazz,s history before he fell foul of the council over the roof PV. The council gave him permission to renovate the house and he did it as per plan. Then the heritage folks dropped on his head and made him undo all the work to the tune of 70,000. He in turn sued the council and took the 70,000 off them. A situation like this is the very very last thing that you want.
                                            Biff
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guydewdney
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« Reply #13 on: February 26, 2017, 12:18:43 PM »

Still nowhere to put a log store....

I'm looking at recoup shower trays. Anyone know how much they are? The retrofit version is 275 quid, which is a long payback time.

The water system is basically lots of small houses. I have 8 cylinders. Mains water is boosted and feeding 3x 450 litre accumulators at 5 bar. This then feeds unvented cylinders in each area.

I am quite concerned....
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gravyminer
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« Reply #14 on: February 26, 2017, 02:07:15 PM »

quote -
Don't discount PV - the limit isn't 3kW per phase but 3kW of export per phase in virtually all cases. Given your predicted loads I can't help thinking that exporting too much will be the least of your problems - you have endless opportunities to divert power, even if it's just taking a bit of chill off otherwise empty rooms. Realistically you're going to have a big year-round demand for hot water which helps a lot here.

Nope, already had this conversation with my dno. It's 3kw or nothing.


I thought the 3kw was an export limit too.

Solaredge seem to have addressed this one and they assured me that it is acceptable to the dno, albeit they might need to have this explained to them by Solaredge.

http://www.solaredge.com/edit-se-product-export-limitation-metering

Alternatively create as much solar generation as possible and dump it all into water and / or space heating with no grid tie ?

Is this project local to you Guy ? or have you sold / will you sell the water mill ?
Its a brave undertaking and I wish you well.
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