System Design

[adman]

Afternoon all,

I'm in the process of buying a house, which is quite large (5 bedroom) and needs a lot of work doing to it. I have ample space, and a south facing roof, and therefore am considering solar thermal and GSHP, and as I'll have some space to plant some trees, a wood burning boiler stove too, with UFH throughout, and I guess an accumulator of some description to mix all three.

Although I've been quite happy sizing and installing my own CH/DHW systems in my previous houses, I think to get this right, given the likely cost, I'd rather pay a professional to design and size the system. However, of course there are professionals, and not so professionals, so (and to the point of my post) where can I go to find a good one, or check whether someone is genuine?

For info the house is in the Ledbury area, so I guess someone reasonably local would be handy. I'll also have install it all over a period as I'll be having to do a fair degree to the house do and can't afford to do it all at once. And the first job will be insulation as it has none in the roof (mind you, doesn't have ceilings in some parts.....) 

Any thoughts welcome.

Thanks,
Adam.

[Countrypaul]

I am in a slightly similar position with extending and renovating/refurbishing a property.

Until the redesign is approved, it is impossible to work out the insulation that will be applied, until the insulation design is complete it is virtually impossible to work out U-values for the walls/roof/floor meaning that calculating heat loss is almost impossible. Without any idea of heat loss and therefore heating requirement, we have no idea on how big a boiler/heat pump will be required. The use of Solar thermal and a WBS is something we also want to include the latter may well affect the sizing of the boiler/hp.
Because a significant portion of this will be a renovation, we are looking at external wall insulation, we are looking at a new roof, and want UFH and will probably have a MHRV system. We are also looking at double/triple glazing, with more windows on the south than north limited by the current design and the fact we are in green belt and a conservation area.

So before we can work out the heating system details, we need to have a very clear idea of the house structure and be able to establish U-values for all the critical areas. I believe a SAP calculation will probably be the most appropriate approach as advised by our architect.

Once we have this, I understand that it will be relatively straight forward for many of the UFH suppliers to design and quote for the UFH aspect and that will lead to a clearer idea of the requirements for the heat supply.

Assuming the above makes sense (and I hope someone will point out all the problems) you might want to start off by designing the insulation before getting in other help to design the heating aspect.

Hope this helps

Paul

[adman]

Good points Paul.

Planning on doing a lot of insulating first, so I think our first winter we'll just have a WBS which I'll connect in to the existing CH circuit. Then as you say once all the insulating is done we'll know what we're dealing with in terms of BTU requirement.

The house needs re rendering, so we may look at external insulation/render systems and see what we can achieve, which i imagine will be pretty darned expensive, so it could be a few years before GSHP is on the cards.

What sort of external insulation are you looking at Paul?

Thanks,
Adam.

[desperate]

Wouldn't you get the design approved with all the insulation specified first? I can't see how you would get approval without that spec in place.

adman,

How to find a decent designer, thats the 64000 dollar question, if you can get some references to follow up, or word of mouth recommendations you would hedge your bets quite a lot.

You say you have designed this sort of stuff before, so why not this time? it's not rocket science, in fact far from it.
Keep it simple is the best rule to follow in my experience. I've seen no end of systems with all sorts of fancy over priced add ons fitted, that really cant justify the extra expense, add to that the complication of setting up such a system and operating it through the year, and a lot of house holders give up and overide the whole lot.
Of course I'm not saying you would do that, but if as lots of others would say here you insulate as much as possible the heat demand would be so low that the efficiency of the heating is quite a low priority anyway.

If designing my system from scratch for example I would have say four or five zones with independant time and temp control, you could heat a Store with the GSHP and the WBS, and then use the Solar for the hot water, backed up by the WBS, or something


Need a bit more info on your specific requirements really but you get the gist.

Hope that helps a bit.

Desp

[Countrypaul]

Adam,

The initial idea we had with the external insulation was a propietry render ontop of resin boards, probablya  total thickness appraoching 75mm.

Due to the planners we have had to change the approach several times and still have not yet got anywhere near their support for a planning appliaction. The latest thinking is proably closer to 100 mm thick total, but posible with a brick finish rather than render finsih. The property currently has the centre built in the 1950 from brick, with different bricks used on extensions at each end and at the rear. Most of these extensions will be demolished and rebuilt and if we are putting on external insulation will probably be built from block rather than brick.

One we have something that the planners are not unhappy with, we will be able to work out the insulation (there is a chance that thicker insualtion will make the property to large !!!) and from that work out the heating capacity required and then decide on which way to go with the heating. Currently a mix of Oil, leccy storage heater and open coal fire, looking at ASHP, and WBS (along with soalr thermal, PV, etc.).

Paul

[wookey]

For EWI look at Weber and Knauf systems. Both offer polystyrene-based and rockwool-based with render finishes.

For calculations SAP is useful but it has some serious limitations, especially as your insulation levels start to get 'good'. PHPP is a lot more detailed and accurate. It does cost money though (GBP 120). I'd do both gvien how much money is involved in doing this properly.

In general go crazy on the insulation and airtightness levels and thermal-bridge reduction. As desperate says, this combined with solar thermal enormously reduces the heating system demands.

[dhaslam]

When you are installing UFH make sure that the  north facing side of the house has  much closer spacing of pipework.    When you have a good level of insulation the south facing rooms will be almost self heating  and you can run the underfloor heating at very low temperatures.   This is a big advantage when heating with a heat pump and in the spring and autumn a single dedicated solar  panel would be enough to keep the system ticking over most days.   

[djh]

Due to the planners we have had to change the approach several times and still have not yet got anywhere near their support for a planning appliaction. The latest thinking is proably closer to 100 mm thick total, but posible with a brick finish rather than render finsih.

Are you in a conservation area or somesuch? There seem to be some helpful planning experts on the greenbuilding forum, so you might find some help there.

[Countrypaul]

Due to the planners we have had to change the approach several times and still have not yet got anywhere near their support for a planning appliaction. The latest thinking is proably closer to 100 mm thick total, but posible with a brick finish rather than render finsih.

Are you in a conservation area or somesuch? There seem to be some helpful planning experts on the greenbuilding forum, so you might find some help there.

Yes, conservation area and green belt - along with unhelpful planners. The building is 1950's brik build dormer bungalow with 1960's extensions(different roof pitches to original), uPVC windows/doors, oil tanks under the (current) bedroom floor, open fire in the louge, very little insulation above the ceilings (even less after we had all teh asbestos removed!). So a major job, given that we want to extend it and convert the garage to a study (as work from home) etc. The conservation officer is keen on keeping a brick finish to "retain the character" even though there are several different bricks used already. Taken nearly 2 years already just trying to get past the planners obstaacles. I would not be suprised if they get upset about the external insulation once they think about it (but hopefully their lack of thought means they won't think about it).

Paul

[Brandon]

paul, tomorrow morning sees me dropping my plans of at the council office.

We are doing a couple of little extensions (kitchen and study) and using EWI on the rest of the original building (1953 council house).

The front is drawn as being slip brick finish, and the side and back will be render.  The slip bricks, whilst being a pain for me due to the extra cost, are there to sweeten the council, as the whole estate is red brick, and we are end terrace of 4.  The RWP is to be reinstalled on the return that will be formed to next door, in an attempt to help disguise the 7" disparity between us and next door.  We are lucky in so far as the hip roof provides us with 12" soffits all around the exterior of the house.

The EWI that we are planning to use is Relius http://www.relius.de/en/_dokumente/englisch/Etic_systems_detail_drawings.pdf these are the details that are quite useful, it is supplied in the UK by http://www.thinjoint.com/ Chris Hirst the MD is a very helpful chap, I would strongly recommend giving him a call.  He can supply your EWI upto 660mm thick IIRC.

HTH

Brandon