Hello experts,I’m new and doing stuff to my house,wanting and not finding much except advertising when I search the title above. I’m interested in getting expert help for layout,and the hard aspects of fitting,but otherwise it’s just me. No interest in government schemes,loads of space for as many evacuated tubes as I like,on both ESE and SSW facing roofs,plus a ton of space for a huge thermal store if I want it. What is the ideal? I mean can it provide all or nearly all hot water and heating in Nottingham? If I could do away with gas,have immersion heater instead,will it make sense over a heat only boiler? The whole system at the moment is ancient conventional,I’m already beginning to fit wet under floor heating for downstairs,and will consider it for the rest of the house if I’m advised it makes sense. Please be kind to me
Thermal store+solar performance
- Thread starter 2felixtoe
- Start date
Sponsored Links
Have you got the thermal load calcs for your house? It's all maths (or physics even)- what is the heat load, how many kwh (or BTUs) will your evacuated tubes provide- bearing in mind that full heat load tends to be in winter when your solar setup may not provide much energy (due to cloud). The thermal store allows you to bank energy but can't create it (so, for example, if your solar panels deliver 2kw for 10 hours into your store you can then extract 20kwh. Which may only be enough to satisfy heat demand for 1 hour in the winter but all your hot water/heat demand in summer)
Thermal stores work well with woodburners/Agas (again banking energy) or these pellet burners, by all means have an immersion heater as a backup but at the moment gas per kwh is much much cheaper than electricity so my suggestion would be to have a gas system boiler as the secondary heat source (assuming you've access to mains gas). Bonus with using gas boiler with a heat store- the boiler will run at full kick (max efficiency) for moderate time periods rather than modulating so your overall fuel efficiency will be better than running the heating directly from the boiler
UFH as the only heat source in the house- hmm. If you're doing major refurb, make sure you insulate the floors (so you're not heatiing the voids), after that it is maths again- how many kwh can the UFH supply per square metre, does that equal or exceed the heat loss for the room? Remember that UFH under furniture isn't going to be all that useful and carpet is a very good insulator.
Also re thermal store- they're quite heavy (when full), if you have suspended timber floors then have a think about extra support (a store for a 4 bed house will be about 400kg full with a typical diameter of 600mm so a loading of 1400kg/sq m.
Thermal stores work well with woodburners/Agas (again banking energy) or these pellet burners, by all means have an immersion heater as a backup but at the moment gas per kwh is much much cheaper than electricity so my suggestion would be to have a gas system boiler as the secondary heat source (assuming you've access to mains gas). Bonus with using gas boiler with a heat store- the boiler will run at full kick (max efficiency) for moderate time periods rather than modulating so your overall fuel efficiency will be better than running the heating directly from the boiler
UFH as the only heat source in the house- hmm. If you're doing major refurb, make sure you insulate the floors (so you're not heatiing the voids), after that it is maths again- how many kwh can the UFH supply per square metre, does that equal or exceed the heat loss for the room? Remember that UFH under furniture isn't going to be all that useful and carpet is a very good insulator.
Also re thermal store- they're quite heavy (when full), if you have suspended timber floors then have a think about extra support (a store for a 4 bed house will be about 400kg full with a typical diameter of 600mm so a loading of 1400kg/sq m.
Well thank you,that seems a good start,thermal load,is there a formula? I mean it’s an 1882 solid walled end terrace,3 storey,3 and half bedrooms,3 are 16m square,one is 6m square,bathroom 6m square,landing 4m square,downstairs front and back rooms 32m square combined,2 and half metre high ceilings,double glazed with upvc,loft insulated normally and to modern thickness,but is a room I would love to convert,so I have that to consider in the heating calculations. I can buy a lot of evacuated tubes if I wish,that was one of the things I’d like to work out,I only have to allow for roof space,as I will have more than the one window I already fitted in the loft. I picked up a £50 18 month old Veissmann heat only boiler from gumtree,so that sounds like it’ll still be useful. The old boiler vents out the chimney,so the new one will need re siting,hence all the questions now,it’s a big change involving me bringing the chimney down,all the way through the house,to reconfigure boiler and bathroom,and using the recess in the back of the fireplaces to run pipes in some good insulation. Layout is good,existing pipes all run up through the house next to this doomed chimney,it’s on the sunny side of the house for the solar pipe work to go the same way,and the cellar sits at the bottom of the chimney too,where I can put almost any size of thermal store. I’m a proper convert to insulated flooring,I did my parents entire downstairs,kingspan pressed up hard under suspended floors,with expanded foam all round the edges and gaps,no ufh though,it was like a miracle. My Mum has never used the gas fire since,so I’m fully onside with that,can’t wait for that feeling in this god damn ancient place! The first thing I did on buying the house was sand and wax the floors. It was three years ago and it is still great,but anyway that means no carpet for under floor heating. SO,like I suggested,even once I’ve done the calculations,are more tubes better? And does the thermal store grow to match the number of tubes? It seems like that would make sense,more of a store for all of that heat,am I doing ok here?
Well that sounds like a project, good luck with it all.
Heat load (or heat loss)- Google it, there are a load of online calculators of varying accuracy. They all make loads of assumptions but your place being of standard construction they'll be close enough.
Chimney- big structural implications there, sure you've looked at all the party wall stuff and whether neighbours have done the same.
More panels being better- yes and you'd need to size the store to suit.
Heat load (or heat loss)- Google it, there are a load of online calculators of varying accuracy. They all make loads of assumptions but your place being of standard construction they'll be close enough.
Chimney- big structural implications there, sure you've looked at all the party wall stuff and whether neighbours have done the same.
More panels being better- yes and you'd need to size the store to suit.
Sponsored Links
Hello,thanks again,I’ll look up those calculators,and have just got drawn off into the world of CIBSE Solar Heating Design and Installation Guide,which might be fun to read as a background! I can fit really a lot of evacuated tubes,so my dream of totally renewable heat is closer to being possible,from what you say,more being better. Chimney is doomed as historic subsidence separated it somewhat from party wall above the level of my highest ceiling,not to mention horrific weathering,so my neighbour’s on board for me to take it all down on both sides of the party wall to the ceilings,and then I’m ok to take out the chimney breast on my side only. It is one of those things where I can’t do one thing properly until the other thing is done properly,on down the line,so if I don’t do this chimney,any future plans won’t work well. It is daunting,I do access work for a living,and have rebuilt,lined etc a chimney for wood burner in the past,but never this. I have talked it through with a number of good builders,so I’m just gearing up to it,any advice would be welcome. More thanks oldbutnotdead,you have a good name,I can only assume you’ve been in this game for a while,and roll your eyes continuously at questions like mine...
- Joined
- 9 May 2004
- Messages
- 124
- Reaction score
- 5
- Country
Regarding the thermal store...go big. I have a 40kW biomass (log) system, for which a 2000 litre thermal store is recommended. I upsized to 3000 and am so glad I did. In hindsight, 4000 would have been better. In the winter, this provides greater leeway as to when I need to light the boiler - it takes a little planning to think about when I'm going to be home/awake etc.
Now, for a solar system, you don't have the issue of manual intervention, but nonetheless, I'd recommend you get as large a store as feasible so that you can capture as much energy as possible. Factors to consider here are: cost, weight/floor loading, and the ability to get the tank into the room where it is stored - mine was too tall to get through a standard garage door without upending it and even when empty it was heavy and involved some rigging to a towbar etc! My tank is an Akvaterm tank and it's fantastic - in the winter, it loses less than 1 degree per day when the contents are >80 degrees. You will also get good stratification where the top of the tank could be easily 40 degrees hotter than the bottom.
Notwithstanding the above, with a solar system, there is a limit as to how much energy you'll be able to collect in a day. There's little point having a store that's capable of storing more than this limit as you'll never fully load it. You'll need to do the calculations to determine what this will be for your setup.
Interesting project. Good luck and keep us updated.
Now, for a solar system, you don't have the issue of manual intervention, but nonetheless, I'd recommend you get as large a store as feasible so that you can capture as much energy as possible. Factors to consider here are: cost, weight/floor loading, and the ability to get the tank into the room where it is stored - mine was too tall to get through a standard garage door without upending it and even when empty it was heavy and involved some rigging to a towbar etc! My tank is an Akvaterm tank and it's fantastic - in the winter, it loses less than 1 degree per day when the contents are >80 degrees. You will also get good stratification where the top of the tank could be easily 40 degrees hotter than the bottom.
Notwithstanding the above, with a solar system, there is a limit as to how much energy you'll be able to collect in a day. There's little point having a store that's capable of storing more than this limit as you'll never fully load it. You'll need to do the calculations to determine what this will be for your setup.
Interesting project. Good luck and keep us updated.
Have you considered a heat pump instead of going all solar thermal? You could have a combined system which would take away some of your dependence on sunlight in the winter but still allow you to capture heat for your underfloor heating.
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
