Heating and hot water for granny annexe

[jamesmcbride]

When we built our "Granny Annex" we went down the LPG / Combi boiler route (the main house is oil fired). It has worked out well for us over the past 5 years and provides plenty of hot water for a single shower and underfloor central heating.

In our situation the annex is less than 20m away, but it still seemed to make more sense to make it a bit more self contained. Also means that if the boiler goes down in the main house, you're not completely without hot water / heating.

 

[pasty_girl]

Thanks again everyone - more food for thought. We have a contact who works with insulated pipe so we are going to contact him. We were thinking similar in terms of zoning valve and separate circuits for radiators and shower/sinks. It's a neat solution but the pipe may be too expensive to justify it.

Dont think we can put the house on an economy 7 tariff as we use all the electricity during the day.

*JamesMcBride* that's interesting about LPG. Do you have cylinders or a tank? Who is your supplier and can you remember what installation costs were??

Thanks again all.

 

[jamesmcbride]

We have a calor gas tank (underground) which I believe is loaned / leased. Not sure on the costs off the top of my head I'm afraid, but it's basically managed by calor themselves, they monitor the level of gas in the tank and fill it up when needed.

Cylinders are another option, and probably a bit cheaper, just not as convenient.

 

[stem]

Dont think we can put the house on an economy 7 tariff as we use all the electricity during the day.

Yes you can, all homes using the economy tariffs, also have the standard daytime supply as well.

There are some disadvantages of storage heating true, but as you would only need two storage heaters, the initial outlay will be a fraction of the cost installing a new gas installation or heat pump, even with the wiring.

 

[EFLImpudence]

That's true but putting the house on the dearer daytime rate which goes with E7 may not be cost effective.

 

[stem]

That's true but putting the house on the dearer daytime rate which goes with E7 may not be cost effective.

The E7 tariffs I used in the past didn't have a higher day rate, but had a higher standing charge. But it was a few years ago.

 

[Iggifer]

Last (and only) time I was on E7. It was about 5p/hour dearer during the day than a flat tariff, but about 7 or 8p cheaper than the day rate at night.

The flat only had electric heating and DHW so was my only real choice. I wouldn't want E7 for a house when the only benefit would be the annexe - you'd lose out I reckon

 

[stem]

I wouldn't want E7 for a house when the only benefit would be the annexe - you'd lose out I reckon

It's not the cheapest method of heating agreed, but mains gas isn't an option here. Oil and stored gas aren't the cheapest either. However, it is important to consider the big picture. Price of storage heaters about £200 each, plus cable / installation (few parts to fail / maintain and no annual servicing costs) Price to install oil fired boiler / stored gas heating and radiators or heat pump will be much more. Installation of an LPG / Oil tank alone would be thousands, without the heating system which would add a few thousand more, plus ongoing service and maintenance costs.

 

[ban-all-sheds]

It will be made from a SIPs construction so hopefully very well insulated.

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any other ideas.

How about building it to Passivhaus standards so that it needs virtually no heating at all?

 

[pasty_girl]

Hi all,

We have spoken briefly to our electrician and plumber and tried to cost up various options.

We are now leaning either electricity with one air pump and one radiator (it only has two rooms), electric shower and instant water heaters for sink.

Or, pipe gas down there and put in boiler.

We think the gas option is £700-£1000 more for installation costs plus the annual boiler service charge so financially it doesn't make the most sense but it's a less "bitty" solution and a dead cert for the shower we hope (slightly worried about the power of an electric shower)...