Some System Planning Help

[wcavanagh]

So, I am renovating a 1900 cottage in Scotland. It is about 180sq meter floor area. Just finished gutting the place back to solid stone.

Starting to make early plans about heating at hot water system. I am 100% going for UFH throughout the cottage, with some very good zone control etc. I think I have most of that covered, found lots of info online etc.

Now my thinking is turned to hot water. The cottage will be 4 bedroom, 1 main bathroom, and 2 en-suit shower rooms. It is myself, wife and baby that will be living here.

I have an outbuilding attached to the house I plan to use as plant room, etc. We do not have mains gas here, so will more than likely go for oil as I get some discount on oil though work.

Anyway, seems 2 options, combi or some kind of system boiler with tank etc. I see advantages of both, only ever installed combi in the past so no experience of other systems. What are peoples general thoughts?

I am keen on economy and still find it hard keeping a tank of hot water hot all the time, seems a waste, but maybe things have moved on.

Would be very interested in peoples thoughts.

Cheers
Will

 

[flameport]

A combi will be useless with 3 bathrooms.
Losses from hot water storage are minimal, all modern cylinders are well insulated.
Most heat losses are from the pipework, which will be the same for a combi or storage.
The cost of hot water heating is insignificant compared to heating the building.

 

[wcavanagh]

Thanks, very interesting. So well insulated cylinder would store enough hot water for showers etc, without any issues. I will start doing some research into what is involved with such a system.

 

[Madrab]

1st thing I'd advise is get a cold water mains pressure and flow test performed, that will give you a starting point as to what options might be available to you.

 

[wcavanagh]

I have already done this, I have a static pressure of 12 bar and flow rate of 28 L / min

 

[flameport]

With a water supply as good as that, a mains pressure unvented cylinder.

Heat losses from a modern cylinder are typically less than 2kWh per day, or in price terms less than 10p of gas per day, or about £30 per year. Not including the fact that for some of the year, that heat isn't actually lost as it contributes to the heating of the building, so real losses are even less.
Oil may be more expensive than gas but the total 'loss' is still tiny.

Various sizes of cylinder are available, and waiting for hours for it to heat up is ancient history - 20 minutes would be more typical.

Some example specifications here: http://www.osohotwater.co.uk/domestic-products/super-coil.html

 

[BigSnoopy01]

dynamic pressure reading is what you want but i cant think yours is not going to be very good with a static of 12 and a good flow rate.

 

[muggles]

A Hounsfield oil boiler linked to an OSO Super Coil unvented cylinder is what you need. If you're going UFH, have a look at NuHeat - they provide you with a full design service and guarantees that the system will heat your home adequately. A bit more expensive than some systems but definitely worth the premium IMHO

 

[wcavanagh]

Many thanks for the input, I will get researching.