New central heating system and range cookers - any pointers?

[larrylamb11]

I am here as a new user, so first off “hello” . I am looking for some advice and guidance on central heating….. Basically I have a blank piece of paper and am trying to work out what to start with regarding a totally new system.
Background: detached cottage of typical 19th century construction, (9in solid brick walls, single glazed, minimal insulation) with new extension under construction (12in insulated cavity walls, double glazed, heavily insulated). New extension is slightly bigger than the old cottage and brings total floor area (ground and first floor) to about 140msq… so space is at a premium. Old cottage heated by night storage on Economy 7 (ouch). No mains gas etc. Extension is to take new kitchen, 2 bathrooms (one en-suite), heating system etc. with provision to supply the old side with heat and an occasional use bathroom in due course. Intention is to use under floor heating in the downstairs of the new bit as the floor slab is insulated, with radiators elsewhere. There will also be a multi-fuel type log burner of at least 4-5kw in the centre of the house providing radiant heat to both old and new sides in the winter months. The kitchen is due to have a cast iron type cooking range installed giving further background heat….
Decisions, decisions: this is where I have got pretty stuck…. Originally we were spec’ing for air source heat pump, but having looked at the cost of install that now seems unlikely. We don’t have enough roof area for solar panels (double pitched with shallow valley) or enough land for ground source. Which has kinda left us looking at (tank fed) oil or gas boilers. This is where it got slightly more tricky owing to the cooking range…. we are coming down to thinking that if we are fitting a range cooker anyway, why not fit a combined cooker / central heating boiler like the Redfyre central heating range cooker – they claim SAP rating in band B with efficiency in the 80% area which isn’t too horrendous. This saves a massive amount of cash (and space) over fitting a range cooker AND a separate modern central heating boiler. We were also thinking of using an unvented mains pressure hot water cylinder. Whatever we use I am quiet keen to have it only just produce enough heat so that I get lots of opportunities to use the log burner (free heat and that warm cosy feeling just can’t be beaten).
So, where do I start??? Try and work out heat loss calcs for the whole house so that I can size a boiler and go from there? Am I going down the wrong route to opt for a central heating range cooker? If I have a range cooker in the kitchen which is all open plan to the dining area and open to the log burner, am I going to need underfloor heating? The area of the open plan space is about 3.5sqm and all of modern well insulated construction. Whilst the floor will be tiled, I am worried that I may end up over-heating the area and never actually use the underfloor heating, in which case I would do well to save the cash and just fit an appropriate (and cheap!) radiator. Range cookers seem to produce upto about 1kw of radiant heat idling. Does anyone know whether a central heating range could actually run underfloor heating and do all the domestic hot water etc. SO many questions – sorry! I hope someone here can help steer me in the right direction and give me some pointers on where to start.

 

[Norcon]

I would just fit a radiator.
Not sure about Redfyres with UFH. The Stanley Brandons can heat UFH but with just one room in your case its hardly worth the bother.
Range cookers are usually best when there's lots of cooking to be done IMO although I know people who just have them as they like the range being the focal point of the kitchen.
Would like a Stanley but don't need that sort of cooking capability.

I have a neighbour with a £6 grand aga in his kitchen. Looks the part I must admit.

 

[Matt 87]

Agreed, stick with a radiator, also go towards a Stanley they are a much better piece of kit than the Redfyre. We advice customers to bear in mind the installation costs for the flue when choosing range cookers as this can a lot more than you would think! Depending on whether you have line the chimney or use twin wall external flue.

 

[Matt 87]

Also go for Oil, check out OFTEC's website for running costs of different fuels.

http://www.oftec.org/comparative_costs.htm

If you don't go for a range cooker or go for a heat only model ie an Aga, then remember that you can get external boilers, check out Worcester's range, good pieces of kit and may get the machine out of your way completely.

 

[larrylamb11]

Thanks for the comments I am looking at a Rayburn 480k and trying to compare that to Esse, Stanley, Redfyre and Heritage versions of similar central heating range cookers...... Chimney-wise I am looking to cut at ceiling level into the the concrete liner of a modern chimney that has just been built - its a modern construction using cast concrete 'rings' backfilled around them with verniculite? is that right? some sort of light insulating material that is mixed with cement anyway. Its a full height chimney and in position for taking the range cooker.
Do you think I would be best to go with a standard vented hot water cylinder, a mains pressure cylinder or a heat store/thermal bank style arrangement? I don't have any loft space at all for feed tanks as the rooms are in the skeelings, so it will all have to be either crammed into a cupboard over the stairs which is only about 1m high or stood in an enclosure on the ground floor (downstairs loo or similar).
How much more expensive is underfloor heating over a radiator?

 

[Matt 87]

Out of the machines you are looking at the Stanley is definately the best then Redfyre, wouldn't bother with Esse or Rayburn at all. Rayburn rely on the link with Aga and that's where the similarities end!
Did you know that Aga now produce a pressure jet burner for the machine, (rather than traditional vapourising type) which means a lot more control over the machine (they still aren't cheap though!)

What is the internal diameter of this concrete pre cast chimney? Yes it is vermiculite they use (looks like small pebbles).

We don't work for Stanley (have done in the past) but trust me if you are going to get a Range cooker go for the Stanley, get an Unvented Cylinder if you can, much better setup, avoid a heat bank and as you have said you can't really install a vented cylinder anyway.

What size is your incoming water main and how far does it run from the road to your driveway? You need to do a pressure and flow test on it to ascertain whether you will benefit from one, there are other options apart from installing a new water main if it is not currently large enough, such as pumps and accumulators but first you the pressure, flow and water main size.

Underfloor heating is A LOT more expensive than radiators, it works very well but I would go for a radiator from what you are saying.

 

[larrylamb11]

Interesting you say Stanley is the best - haven't been able to find much info on them. I have been going off the range efficiency site here: http://www.rangeefficiency.org.uk/rcresult1.php to guage the usefulness of the various machines and the Rayburn had come out quiet well - its a twin pressure jet burner jobbie with modern type burners. I will try and find someone who knows about Stanley ranges though at that sounds interesting.
The concrete liner is approx 25cm / 10in internal diameter. Mains water flow seems to be pretty good here - its black plastic in the ground so it can't be too old and the pressure appears more than adequate - it needs officially measuring but I would be surprised if it came up short.
Thinking about unvented cylinders..... some people I have spoken to suggest getting it as close to the kitchen sink as possible, others say put it anywhere it will fit.... I would welcome any advice on this. Would it be a bad idea to fit an unvented tank in a bedroom from a noise point of view? I am guessing they must make some noise when they are heating up or water is being drawn off. Equally, if it is mains pressure does it really matter if it is any distance from the kitchen sink as it should fire hot water through at such a pace there won't be any need to worry about heating up the lenght of pipe in the run.
What do you suppose would be the right sort of size (litres) unvented tank for a four bed family house? Has two bathrooms (one with bath, both with showers), kitchen, another basin and potentially one more bathroom (if we can convert a loft!)... usual domestic usage.

 

[Norcon]

some people I have spoken to suggest getting it as close to the kitchen sink as possible, others say put it anywhere it will fit.... I would welcome any advice on this.

Fit the cylinder as centrally as possible in relation to outlets.
But bear in mind UV cylinders have discharge pipe and f&r pipe to be configured.

Would it be a bad idea to fit an unvented tank in a bedroom from a noise point of view? I am guessing they must make some noise when they are heating up or water is being drawn off.

You'll get the noise of the motorized valve opening and closing!
Any other serious noise and a problem has arisen.

Equally, if it is mains pressure does it really matter if it is any distance from the kitchen sink as it should fire hot water through at such a pace there won't be any need to worry about heating up the lenght of pipe in the run.

Water regulations state the hot water distribution system should provide temperature of 50c within 30 seconds after opening a tap!
You can calculate pipe volume and maximum pipe length based on flowrate to stay within this criteria.
All distrubution pipe should be well insulated.

What do you suppose would be the right sort of size (litres) unvented tank for a four bed family house? Has two bathrooms (one with bath, both with showers), kitchen, another basin and potentially one more bathroom (if we can convert a loft!)... usual domestic usage.

210/L

 

[Matt 87]

Agree with all of the above.

 

[Matt 87]

Agree with all of the above

 

[Matt 87]

Agree with all of the above.