Installing a whole new central heating system - options?

[Wightsparks]

I looked at this about 9 years ago (planned, specced and installed it all myself and it's still working!) I went for a thermal store/heat bank - 500l of well insulated water tank.
This tank is be heated by:
- solar hot water, (separate circuit)
- 2 x 6kw Immersions (on cheap electric overnight if needed)
- multifuel stove (7kw to room 18kw to back boiler)
- I can also plug in anything else in the future (I designed for a heat pump but decided to wait to see if needed)

For rads I used the skirting board type with individual room stats and an over all mixer at the tank, hot water is via a pumped heat exchanger so you get mains pressure hot water from a vented system (no expensive regular inspections).
It works well, except it is designed for a constant low level heat so it takes a while to get the whole place warm from a standing start.

Also not sure how a local plumber would react! (no it was not completely finished at this pic)




I got the tank from DPS that then became these guys http://www.heatweb.co.uk/

 

[addjunkie]

We are rural with no gas ...recently refurbished the house top to bottom floors out and back to bare stone....

Looked at the rhi pellet boiler thing domestic not really worth considering comercial was, not sure now. In the end opted for an oil condensing boiler, this intern heats a large hear store tank, this tank then also has coils from other heat sources and the ecoboost from the solar not used or exported. Its large enough to store 24 hours worth of heat for the house. In winter most of the heat is supplied by a log burner with a back boiler burning wood. It burns out through the night but has put enough heat in to last the next day as long as you dont want 2 baths at 4 before youve lit the fire.

House full of modern insulation and underfloor heating. Sounds complicted but works a treat, cheap as chips to run as I get free logs in exchange for fishing!

Im about to convert my barns in to 1 bed holiday cottages, these will have simple electric boilers, hotwater tank , underfloor heating, with solar panels for electric any spare into the hotwater.

 

[Mr Fro]

For rads I used the skirting board type

I put Thermaskirt in when I did my last place (small 2 bed terrace). I really liked it and it's very easy to fit but it did take a while to heat the place from cold. The big drawback is if you put something in front of it then you've just lost x meters of heating.

Last year I finished up my current place (big 4 bed detached) also in the sticks and on oil. One of the first things I did was scrap the old system and fit new as the boiler was on it's last legs and the rads were in funny locations and decrepit. Anyway, I went with conventional rads to keep the cost down and "proper" size copper. I also had a couple or rads bent to fit the bays downstairs.

I put in an unvented system running 2.5bar on the HW with a grant vortex pro and I'm very happy with it. I considered a combi but apparently the oil ones aren't great.

The Joule cylinder I fitted (200 or 300L I think) has a secondary coil so I can nip a solar thing to it if I ever feel the urge.

 

[Phil_D]

What’s the benefit of going for a condensing oil builder + water tank over a combi boiler other than negating the risk of losing both hot water and heating if something goes down?

Some great input on this thread, given me loads to think about

 

[julianf]

There is one benefit in that its easy to add other sources to a tank, whilst not really that easy / possible with an on-demand source.

Eg our oil boiler is (will be) hooked up to a thermal store (thermal store / water tank - makes no difference for this explanation) that also has an input from our rayburn cooker, and also has a solar coil.

The disadvantage of a tank is that you either need it mains pressure (which should be commissioned, and is not so easy [possibly not allowed in the uk - im not sure] with solid fuel heat sources, or you need a headder tank somwhere to generate the pressure for the upstairs.

A thermal store has a DHW coil so mains pressure (well, not quite, as you drop the pressure for the coil) evreywhere.

You still need a headder for a thermal store though, above the highest rad, as otherwise you would never bleed them.


If you ever consider getting a solid fuel "wet" stove, then you wouldnt want a combi. Likewise if you would ever add solar thermal. My friend even had their lister CS water cooled engine plumbed into their thermal store.... But if youre sure you are never going to use any other heat source other than the oil, then, reliability aside, i cant see a combi being a bad idea.

We have an immersion in our thermal store. Ive never used it - not even bothered to wire it up. But you cant even (easily) have one of those with a combi...

 

[Burdekin]

We have a Grant combi, works a treat. A combi system is simple and mains pressure hot water straight from the boiler. The old combi lasted for a long time and no issues with the new one.

 

[julianf]

I think some combis get crazy, with pcb control panels and the like, but they dont have to - they can all be done with just simple pressure switches and stats.
I would imagine the latter to be more fault tolerant.

I dont really know why, but oil boilers (from what ive seen) always seem to be simpler, electronics wise, than gas anyhow. Probably as the burner pretty much governs itself, and has its own "brain" so its all separate from the rest.

I would say that you should get a unit with a riello burner - not because theyre the best or anything, but just as they are the most common, so, if it breaks, you just go on ebay and grab another cheap used one that day, rather than searching out some odd brand.

 

[Kayos]

Re the unvented, pressurised cylinders. The CAN NOT be connected to an uncontrolled heat source in any configuration or with any kind of valve. It’s in the G3 document.

I don’t think you can even use a plate heat exchanger, alltho that would be pointless on solid fuel anyway

 

[thinfourth]

What’s the benefit of going for a condensing oil builder + water tank over a combi boiler other than negating the risk of losing both hot water and heating if something goes down?

Some great input on this thread, given me loads to think about

After spending a week without heating or hot water many years ago

it is a massive advantage.


Also if our last boiler had been a combi we would of gone for weeks at a time without heating or hot water as it was an unreliable piece of garbage.

the main advantage of a combi is you don't have a hot water tank beyond that i can't see any other advantage

 

[wookie]

Combi pros and cons...

Pros
- you don't need a tank
- can be cheaper to run since you're not heating water until you need it

Cons
- if (when) it fails you loose both heating & hot water
- more complicated so more to go wrong and more expensive to fix in general
- filling a bath is hard to impossible, too fast & only lukewarm water, slower flow is hotter but bath goes cold before it's full...
- more expensive than a conventional
- can't add other sources of hot water easily i.e. immersion heater
- if you demand hot water for a long time the central heating doesn't get a look in so house cools down
- water temperature is dependant on flow so if you turn 2 taps on they both get lukewarm water
- water flow has to be slower in winter as the incoming cold needs longer in the boiler to heat up

Can you tell I'm not a fan of them yet ?

I've had one, it broke down repeatably, never again. If I ever bought another house with one in the first thing I would do is rip it out and chuck it in the nearest skip as that is the best place for them IMHO.

 

[Burdekin]

We have two combis and both are reliable. Regarding the hot water, it is mains pressure so my shower is steaming hot and powerful and we have sized it so we can have two showers at the same time. Fills a bath in no time and there is no way you could sit in it without adding cold water. You're not having to heat a tank with electric so is cheaper and less wasteful and you don't run out of hot water with a combi also.

 

[julianf]

Re the unvented, pressurised cylinders. The CAN NOT be connected to an uncontrolled heat source in any configuration or with any kind of valve. It’s in the G3 document.

I don’t think you can even use a plate heat exchanger, alltho that would be pointless on solid fuel anyway

That's actually what i thought, but im sure ive seen them in use with solid fuel appliances abroad. I mean in the (kind of) sensible places, rather than the wild west... Maybe theyre just more tolerant of death!

 

[Kayos]

That's actually what i thought, but im sure ive seen them in use with solid fuel appliances abroad. I mean in the (kind of) sensible places, rather than the wild west... Maybe theyre just more tolerant of death!

The safety’s will just keep opening and waste water, plus if they get really really hot then they don’t self reset

 

[gaz1]

a large rocket stove water tank has been built

http://woodstoves.forumotion.co.uk/t850-2600-gallon-rocket-water-heater

 

[8ob]

I cant comment on a heating system but can highly recommend a Farm2000 boiler or equivalent , forget the accumulator or grant scheme along with all the hoops that they make you jump through and just fit one. There's no need to chop things up small because they will burn anything you can physically lift into them including wet fresh cut timber, the contents of the dustbin, leaves and any other garden waste. They are fan controlled with a shutter system so when on demand the fan brings the fire into life instantly, when not on demand there is just a smouldering bed of ashes, this makes them very efficient and controllable. I know of two that are installed and the owners are both very happy with them, it will be my next boiler of choice. Worth putting on a stand so you can rake the ashes straight into a barrow and throw stuff in without having to bend down.

Bob

Farm2000 http://www.farm2000.co.uk/

 

[julianf]

Id like one of those - i wouldnt even have to saw up the pallets then!

 

[gaz1]

homemade boiler

and smokeless

 

[8ob]

Id like one of those - i wouldnt even have to saw up the pallets then!

Exactly that, I just tip off artic loads of green timber like the one below and they launch it straight into their boilers as is.


Bob

 

[julianf]

...thinking about it, im sure i was talking about a boiler for burning whole pallets here once before, and everyone said it was a duff idea, as there would be too much air space. Im still not convinced! : )

 

[armalites]

@8ob

How much would a load like that cost and how far do you travel?