UKC

Hello, I'll soon be starting work on a Victorian terrace house. It's currently a band F and I'd like to significantly improve this. Looking at energy reduction rather than generation (ie, no solar panels ect).

One idea is to fit a log burner with back boiler connected to a heat sink radiator in the landing and a water tank upstairs. This is to run in conjunction with a combi boiler, the idea being that the log burner will provide hot water during the winter.

What I'm trying to figure out is how to connect the two systems. Obviously it can't be connected directly to a closed system but could you put a tap on the hot water pipe somewhere to control the source? This is the best solution I can think of (or more accurately the best one I can do myself), any other suggestions?

Also looking to insulate the house as much as possible and fit some good quality double glazed Windows.

Is there anything else I can do?

In reply to shaun l:

There are various options with the tanked hot water, hich you go for will probably depend on what type of boiler you have and what its maximum inlet temperature is. There are also various legal restrictions on what you can and can't do with plumbing that could cause the mains supply or your drinking water to be contaminated, also for pressurised hot tanks.

If you do go for it it's worth considering getting a tank with an additional heat input coil for a future solar-thermal input in the summer when the fire isn't being used.

Look up combining solar and combi boilers on google. There are various schemes from the simple (feed hot into a modern electronically modulated boiler) to the more complex based on hot-cold thermostatic mixer valves.

Reducing losses: Do the cheap/easy stuff first then see where it gets you. Draughts, attic, curtains/shutters, carpets/rugs, windows, underfloor and wall cavity or additional interior/exterior insulation.

Obviously some of those you might want to plan for to avoid redecorating or relaying flooring.

jk

I have a log burner, back boiler and a separate hot water system.

I think there is only one make of log burner that has a back boiler rated for a direct system (sealed with expansion vessel). You also have the added problem that if they are coupled you need to be sure that if the fire is out the central heating isn't warming the back boiler!

In the end I went for 2 systems. The log burner heats the lounge and by convection the dining room. The back boiler does the hot water and one radiator upstairs. This give a background heat level. The central heating then does the individual rooms.

As mine is all electric, the backup to the hot water is immersion, but in your case you could use a dual coil tank with the central heating on one and the log burner on the other. You wouldn't need immersion (although I think dual coil tanks have space).

I find that I use central heating every day, but the log burner at weekends means the central heating doesn't need to come on until I need the bedroom and bathroom warm.

I don't know if this will change you band from F - I don't know how they calculate it but I doubt they do it properly. Have you considered an air source heat pump - you can connect those in with a gas boiler I believe.

In reply to jkarran: Thanks, I'll look into a duel tank however the budget won't cover solar panels anytime soon unfortunately. The house is getting refurbed anyway so looking to get all the insulation in first.

In reply to Philip: Cheers, looking to install it myself so anything too complicated is out the question which is why I'd like to keep the systems separate. With regards to the duel tank, does a combi not heat water direct from the boiler so no tank required? Was hoping to just install a cheap tank purely for the boiler then switch between a direct feed from the boiler (in the summer) then use the hot water tank in the winter.

In reply to shaun l:

It does if you buy a combi but then you'll have two different hot water systems. One will be high pressure and one low pressure. This might be a pain with your shower and taps.

In reply to Philip: <shuts eyes slaps head>

In reply to shaun l:

The single system solution feeds warm water (from a heat exchanger coil in a hot store tank) to a modulating combi boiler, it burns less or no gas heating it from warm to hot as required. Not all boilers can cope with hot inlet water and in any case your back boiler may make your hot water dangerously hot so you'll be wanting it blended with cold in a thermostatic valve anyway for safety. If the combi can only take water up to say 24deg then there are other bypass/blending schemes downstream of the boiler that you can employ, the boiler then only kicks in when the tank water isn't hot enough and a thermostatic valve opens to draw from the boiler. The regulations look to be a bit of a pain so you may want to run it past someone knowledgeable to make sure it's safe and compliant. For that matter you may be obliged to run the design past your water company for approval.

Flat plate solar isn't very expensive especially if you're doing the work and sourcing parts.

jk

In reply to jkarran: So the boiler is fed from the tank, which is fed from the header tank, all the water goes through the boiler and the boiler heats up the water if needed? This sounds like a good way to deal with the pressure issues (at a guess), will look into it. A new boiler isn't out the question so I could just get one that allows a hot water feed to bypass all the blended complicatedness?

With regards to the solar, would this be connected to the mains as well out would you just put one up purely for water? Guess all that would involve is connecting the panel to an immersion heater in the tank providing hot water in the summer?

In reply to jkarran: As to your other point I think you need planning permission for this, from what I've read the council come round to inspect before, during and after the work, will need a plumber to install boiler anyway so hoping I can pick their brain too. Hopefully this will prevent me blowing my new house up

In reply to shaun l:

We have a 250lt water tank which does mains pressure hot water indirectly (exchanged through a coil at mains pressure). The tank is heated directly by a multifuel rayburn, which is also directly pumped around the hot water radiator circuit on our timed system, and if necessary to dispense excess heat if the water in the tank boils (we boiled it in 1.5hrs the first time we fired it up... ...oops). The tank in addition has 2 immersions, 1 for rare use as a top up, and 1 on econ 7 for occasional timed use during winter. There is an additional indirect heat exchange coil for solar thermal, and a further large heat exchange coil for a different main heat source, such as an oil fired or pellet fed boiler (the latter we currently don't use, but we wanted to have the option if necessary).

Wouldn't something similar work for you?
http://www.mcdonald-engineers.com/thermflow.html

With regard to victorian housing stock... I've renovated a victorian flat before. Stone and brick walls, thick but 1 layer, traditional cornicing, ceiling roses etc, lathe and plaster, suspended timber floors, old fireplaces in most rooms, leaky doors, skirting etc. What I did was double glaze, take out lowered ceilings that had been placed before me. Take up laminate flooring. Exposed trad features that were hidden. Made an open fire in the main fireplace to make an open fire. Sealed up the other fireplaces etc. Fitted thick curtains. Sealed and sanded the floorboards and skirting elimninating major leaks. However, the temperature was very difficult to maintain, especially in a windy winters day, and cost alot to heat. What I'd do now would be to take out the lathe and plaster walls and fit plasterboard fronted 50mm kingspan to all the walls, lift the floor and insulate between the joists and place a chipboard floor with carpet on top. If you want to keep cornicing, you can cut just below it, but I'm not sure its really worth the time and the effort. Double glazed, and make sure particularly the front and back doors are done well. For us, the major issue was air coming under the floor. I would definitely go for stoves, back boiler or not, but don't put in an open fire!

I hope that helps!

In reply to shaun l:

There are 101 ways to skin a cat but the simplest I've seen looks to be using an unpressurised storage tank heated indirectly by your log burner*. Mains pressure cold water flows through a coil in that tank picking up heat** and on toward the boiler.

If the boiler can take hot water in then the job is simple. If it can't you feed the boiler cold water and you blend the tank-heated water with the boiler water at the boiler outlet, if the tank is hot enough the boiler will light briefly then go out once the thermostatic blending valve comes to operating temperature and shuts it down. If the tank is cold your hot water comes solely from the boiler.

* Solar thermal (water heating) panels can heat this tank via a separate heat exchange coil in the same way the back boiler does.

** To avoid scalding you may want/need this output blended with cold.

There are water hygiene issues with standing warm water so you'd need to look at the regs to ensure it's safe and you're allowed to do this in the uk.

jk

In reply to Jimbo W: Cheers Jimbo, sounds pretty much exactly what I've got in mind. A few things I couldn't find answers to is is it worth insulting the internal walls that join the adjacent houses, and is there any benefit to insulating the two internal floors (loft is converted so will be insulated on the underside of the tiles). My approach is the more the merrier.

In reply to jkarran: Ta dude some really helpful advice there.

In reply to shaun l:

I should add that in our heating system the hot water to the taps is blended to maintain it at a max 60degC. Very simple to do that. The other thing is that one thing you can't really do is have a log burner back boiler, and conventional boiler both *directly* feeding heat to a thermal store. The back boilers tend to put alot of crud into the system, and many boilers just will not like that. Also because the heating system from back boiler to 250lt tank is one system, that means you need to inhibit that entire volume, i.e. you'll need to add about >50lt of inhibitor, which is expensive, but more to the point, means you want to make sure that when you institute the system that you have it all sorted before you add the inhibitor, because you really don't want to have to drain the system and have to buy more inhibitor.

Incidentally, why not solar water? It is one of the cheapest renewables, and performs really quite well? If its a money thing, you could make your own! If you are getting a thermal store, I'd make sure you've got an additional coil or two for solar water or some heat pumped system so you have future flexibility.

Pay the £5 to the green building forum and ask your questions there (you can read past stuff without paying). The forum doesn't look like much, but there is alot of know how, and good people to ask questions to, which certainly made my £5 well worth spending.

In reply to Jimbo W: Not sure if I'm following you here, thought the pipes came out of the boiler then ran through a coil in the tank, so the log burner water never meets the tank water.

As for solar water all the systems I've seen are thousands of pounds, which system do you mean?

Will check the site out sound spot on

In reply to shaun l:

That would be an indirect system. The problem with that system is that if the system isn't very efficient at getting rid of heat you can get much expansion within a relatively small volume of the back boiler and related pipe work. I think it is possible, but it wouldn't be my favoured choice, especially with more modern highly efficient stove back boiler setups. I do know one family who directly feed three rads off of an old stove passively with a back boiler, but not a hot water tank, it knocks alot when it gets hot. Does that make sense. You have to get rid of the heat you make efficiently to prevent expansion within a confined space. Our system is direct.. ..back boiler water is the same as the main body of water in the tank. If the water in the tank boils, which it has for us (>355lt worth of water), the pressure produced can be released as steam via the integral header.


http://www.naturalsparx.co.uk/product/1051030446/Dimplex-6SQM-Solar-Thermal...

Something like that along with RHPP, which is I think £600. So you should be able to get the main kit for not much > £1000. You may well be adding the thermal store as discussed above anyway, esp if you are wanting to integrate a stove back boiler system. So the only other costs are the trickle pump to move the fluid through the solar water system, and installation.


It doesn't look very grand, but I've had much good advice over the years.

In reply to Jimbo W: Right, with you now. The direct system all just looked a bit complicated for me. From what I've read a heat sink radiator should solve the boiling problem because it's always losing heat, so the pipes go straight through the radiator with no valves (so it can never accidentally be turned off), through the coil in the water tank and back. This gives me the bonus that I can have a radiator on the first floor that's always on when the log burner is.

As suspected the solar's a bit too expensive atm, (so is the log burner really Something to think about though, thanks for the link.

In reply to shaun l: Before you embark on this project see if you can get access under the ground floor (assuming it's suspended timber). If it's anything like ours from 1898 all the joists will be rotten so you may as well replace it, kingspanning between the joists. Ours was 4x2 joists, we fitted 6x2 ones to allow us to fit 150mm of kingspan between them and simply notched them down to 4" where they sat on the sleeper walls. You NEED to have good airflow under the floor to stop rot growing in dead air spaces, but you can insulate the room above from the cold air underneath.

In reply to shaun l:

Its a simpler system if you ask me!


You should always have a heat sink radiator, even in a direct system, otherwise, how would excess heat (say its boiling) in a thermal store get safely reduced. Our radiator circuit is 5 rads. The bathroom rad is always on and fully open. If the temp reaches 95degC, the radiator pump starts irrespective of the room stat and heating timer. If all the rads are off, the bathroom can still disperse heat. Does that make sense? A heat sink radiator will need to be big enough/a sufficient size to exhaust any excess heat.. ..I'm sure the guys at the greenbuildingforum will be able to help out with that.

In reply to shaun l:


I understand. The most important thing is that you give yourself the potential future flexibility, at minimal extra cost, to be able to adapt in the future, when solar costs come down, or when you have more savings etc. What I mean is, if you're getting a thermal store, make sure its got the extra coils if you decide to use them in the future.

In reply to Toerag: Cheers, was wondering about that. Did you fit the kingspan touching the underside of the floorboards? A tad confused about the air gap you mentioned.

In reply to Jimbo W: Morning, spent half the night learning how to make solar thermal panels, think that one might be a goer. When I've heard solar panels before I've always thought of the electric ones, didn't realise you guys were talking about something so much simpler.

Did you get epc ratings before and after the work? Curious what the difference was.

In reply to Toerag: Oh wait, know what you mean now, by sealing the cellar you're changing the airflow in the cellar so need to provide another?

In reply to shaun l:

Good man! A friend made two large panels for <£500. He used a fish tank lid, backed and bordered internally with kingspan, added a metal sheet, painted it with black mat stove paint, added pipe work runs up and down the panel, all painted mat black (can't remember what the pipes he used were), sealed it all with silicon covered with double glazed box. It worked well even in NW Scotland.

Another friend made solar panels from single sheet radiators, again painted matt black, again sealed inside some kind of glass fronted wooden built insulated box. He said they worked well, but I never saw these ones!


No, so can't comment.

In reply to shaun l: In terms of thermal efficiency back boilers are quite inefficient, I'd personally go the whole hog and get an automatic feed biomass boiler* from someone like Tundra, if i wanted to maximise the energy savings in the house... Then if you want convective heating in your main living space, install a small simple logburner.

*in practice works just like a combi boiler, but needs topping up with wood and the ash pan emptying once a week.

In reply to shaun l:

The joists under the floorboards will rot if air flow isn't maintained. If you're sealing the floor by placing kingspan between the joists two things will happen. 1 less airflow up through the boards so less airflow overall and 2 a colder subfloor with increased likelihood of condensation. You will need to make sure you have sufficient airflow. When I did this we added another couple if air brick vents.

In reply to shaun l:

Solar hot water is easy and cheap to install. Ours cost about £700 including a second-hand 160 litre copper cylinder, which I plumbed in tandem with the main house cylinder so as to pre-heat the water entering the house. In high summer it is achieving 60 C by the end of a sunny day, meaning the boiler seldom kicks in at all.

I got all the kit from here: http://www.solarproject.co.uk/

Read about my project and see some pictures here: http://www.diynot.com/forums/viewtopic.php?t=255833

In reply to shaun l:

Is it a better EPC you want or better energy efficiency? They may not be the same thing.

You may achieve good energy efficiency at reasonable cost doing the work yourself (DIY solar, insulation and woodburner etc) only to find the EPC is unchanged because the work/kit isn't certified/verified by an approved contractor. I may be being overly cynical but you should be wary. If the EPC is valuable to you an approved contractor here and there to tackle the big items may still work out cheaper net.

jk

In reply to jkarran: It's kind of both, planning to sell the house once it's done, buy another and do the same. Not particularly bothered about profit margins or any of that bollocks, just want to make high quality energy efficient houses and hopefully make a living from it.

Increasing a houses epc by two bands can add 16 grand to an average home, so I should be able to recoup my losses at least and learn some skills that are going to become increasingly useful.

I'm going to check all this out with the council before I start, just at the ideas stage atm. Whether or not it improves the epc I'll probably do it anyway, just think it'll be great fun and I figure I can keep it occupied for a winter before selling and show potential buyers the energy bills.

In reply to Rigid Raider: All set on making my own now! Have been looking at second hand kit though, where did you find the cylinder?