Complete Heating System

RoundyDuffy

Id like to get peoples opinion of my idea to heat my house.
Im planning on building a two storey block house roughly 2500 sq foot. 200mm cavity with full fill insulation and warm roof (hip). Basically well insulated!!

anyway my idea is to build a tank in center of the house downstairs about 1 meter square to store hot water. At 2.6m ceiling height gives about 2600 liters of water (neglecting the volume of coils etc).
I want to use rolls of cheap plastic pipe to make coils with both ends of each coil going to the hotpress above so no breaks in the walls for leaks.
There will be 3 heating coils at the bottom solar, solid fuel stove, oil back up.
Midway up (where water is not too hot) there will b a coil for underfloor heating and at the top (hottest) a large coil for domestic hot water.
Ive put it to a lot of friends/lads I work with, and no one can come up with reasons why it wont work.

Here are just a few questions or statements ive heard already

Q. Why?
A. To be different. Prove it will work

Q. It will leak and burst and you will drown in boiling water!!
A. No it wont. It will be a reinforced poured concrete tank.

Q. Why not outside/underground it would be safer and no loss of space?
A. It will lose too much heat. When in center of house any heat loss goes to rooms or upstairs.

Q. How will it be heated?
A. Solar panels heat the bottom coil and therefore the tank for the summer months. In autumn and spring stove lit and weekend will keep tank warm and in depths of winter oil burner may be used with the stove.

Q. How do you heat house?
A. When there is a need for heat you turn on the ufh pump which pumps through the center coil giving warm water.

Q. Hot water?
A. Instead of having a hot water cylinder, incoming water (from attic tank/mains) flows through the large coil at top of tank and straight to taps showers etc. There will b a store of hot water in coil and by the time cold water passes through coil it will be heated sufficiently.

Q.What if coil leaks?
A. All coils go through the ceiling into hotpress which will have removable insulated floor. And any faulty coil can simply be pulled up and replaced.

Hears a s**t sketch obviously not to scale





Any thoughts?

RoundyDuffy

new pic

http://i54.tinypic.com/2eaj59f.jpg

foundation10

When you say you will use cheap plastic pipe for the coils do you plan to attach the flow from the stove to these coils?

L driver

Hello
I think Heinbloed will be needed! The tank may not be as straight forward as you hope. Look in heating and plumbing at a thread about electric UFH and the afore mentioned HB has posted some very useful links and information about this sort of set up. Alot of calcs are required, probably the best way forward though wwith more ST.

RoundyDuffy

foundation10 wrote: »

When you say you will use cheap plastic pipe for the coils do you plan to attach the flow from the stove to these coils?

No the sketch is inaccurate there. I want to use copper to go up into the hotpress then connect to the heating coil. When i say cheap plastic i mean the cheapest that can survive the temp extremes

MicktheMan

I'm not a plumber so will leave the plumbing observations to others.
But here are a few non-plumbing questions.
How will you deal with the moisture escape especially during wintertime?
As you havent mentioned insulation of the tank, so how do you propose to deal with excessive overheating of the house during the summer?
Do you think you will be able to insure the house?

imitation

Have you done the calculations on how much is required to heat that volume of water ?

Have you taken into account it may take a lot of time to bring the tank to usable temperature ?

Are there any concerns with legionnaires ?

Those are the things that jump to my unqualified mind anyway, but it will certainly be interesting.

sinnerboy

Have a look here for "ballpark" of this concept

To produce 50 to 80% of the heat for a well insulated detached house solar collector is a REQUIRED 30-70 m²

A large buffer memory with integrated hot water heater stores the solar heat for heating and hot water for several days or even weeks. The storage volume is designed for solar houses with a solar cover ratio of 50 to 80% with 150 to 250 L per square meter of installed collector area. When completely solar-heated houses even more memory in the order 40 m³ are needed

These qoutes are Google translated from German but you can clearly see the scale of the installation required .

Quite honestly - if you want my advice - concentrate your creativity and focus into reducing your demand for energy by building a very highly insulated and air tight building . Heating one of these is very simple then .

RoundyDuffy

MicktheMan wrote: »

I'm not a plumber so will leave the plumbing observations to others.
But here are a few non-plumbing questions.
How will you deal with the moisture escape especially during wintertime?
As you havent mentioned insulation of the tank, so how do you propose to deal with excessive overheating of the house during the summer?
Do you think you will be able to insure the house?

Insurance!! Never even thought of it and that will prob be the biggest problem.

As for insulation, kingspan all around top and bottom with u value 0.2. Assume 80 celcius throughout tank and room temp of 20 celcius. with a area of roughly 12m2 gives heat loss of 0.2x12x60= 144w

So there should be less than 200watts worth of heating in the house due to tank, not a big problem.
Neway in ireland i dont think we will ever have to worry about over heating

Oh and the tank would be epoxy sealed to prevent any moisture

RoundyDuffy

imitation wrote: »

Have you done the calculations on how much is required to heat that volume of water ?

Have you taken into account it may take a lot of time to bring the tank to usable temperature ?

Are there any concerns with legionnaires ?

Those are the things that jump to my unqualified mind anyway, but it will certainly be interesting.

No calculations really done yet. The point of this really is to keep the house at a constant 20c year round and have constant hot water 24/7. It will all be automated. Im an electrician midway thru my elec eng degree so should have that covered. Want to b able to light the "cosy fire" all day sunday in winter and then have enough heat built up to last the working week.

Tank will only be warmed up from cold once then alwayss kept constant ~80c

Legionaires is only really a prob below 60c.

Therostatic valves to be fitted on ufh and dhw

RoundyDuffy

I like the links sinnerboy thanks. Thats basically wot im talkin about except they wall year round storage as i only want week or two. I like the "memory" incorporated into the curved stairs.

Goin for well insulated house with min 200mm pumped cavity, insulated cavity closers, hrv etc.

I dont like any fancy new build concepts or timberframe. I want a good solid concrete house always warm and cheap to heat.

Radiotower

I'd imagine the whole thing would work out very expensive taking into account getting a structural engineer to design the RC walls, floor and foundation, getting a reputable contractor to build the tank to the required standard to make it watertight, etc. The amount of solar panels required, the size of the boiler... Whats the lifetime of the tanking system you're thinking of using?

Its a huge amount of water to try and heat making it a slow and unresponsive system. Would the amount of oil required in the depths of winter cancel out the saving made during the summertime using the solar panels?

Could moisture still escape through the removeable floor increasing the humidity of the house? You'll prob need a heat recovery system anyway if you are going for a very highly insulated/air tight house.

I'd be worried about children finding the removable floor and removing it and possibly falling in.

Better fill it up before the water rates come in:D

Basically I cant see how it could pay for itself, maybe it will but I'd imagine over many years - maybe more years than the solar panels/water proffing/boiler are guaranteed for and then your into another capital outlay to replace them before the original system has paid for itself.

There's alot of calculations to do!!!

beyondpassive

Well done Roundy for the innovative solution.

This concept of a large internal thermal storage is used in Germany and Hollan and is called the Sonnenhaus concept. It stores excess summer and autumn solar in the a central tank, often placed in the centre of a curved staircase. Theres a house in germany who fill their pool from the seasonal store for a new year party every year.

The concept is a good one, but is not suited to low energy houses as, the store overheats the house. Lars Peterson in Galway has put his seasonal store underground and outside the footprint of the building. Other solutions put the excess solar heat indirectly into the groundwater in the summer, this aquifer moves about 16 meters a year and can be extracted from a bore, 8 meters downstream. Combined with a heatpump this can provide a good source of heat.

+1 to sinnerboy, get the fabric and ventilation right and the peak heat load for a 300 sq meter house can be down to about 3kW for space heating and about the same for hot water. If you store 20,000 litres of hot water, you have to raise all that water over 60 degrees once a week. An insulated tank that may be 80 degrees in september will equalise a lot of heat into the house . 0.2 u value is completely insufficient, sonnenhaus has about a meter of EPS.

One builder i know of is proposing a slab 3 foot deep, built as an EPS raft, with excess solar pumped in to create a thermally massive store. Hopefully it used recycled blast furnace slag instead of cement. What a toasty floor that would be.

Good luck to you on meeting all your heat needs through the solar. My advice is go as far passive as you can first, and have a cooling strategy.

beyondpassive

Interseasonal store

http://tonyshouse.info/

skooby

Like yourself I am always trying to look for the new way to be green. I have no training in this but have asked the questions before. From the info I got a tank the size of yours heating water from 15 deg to 80 deg would require approx 200kw of heat. The highest output solar panel I could found was 5kw per day. This would mean somewhere up on 40 panels. I found a stove with 30kw output. I was told by a plumber that in simple terms it would take up to 8 hours of burning without taking into account heat loss or distribution.
Another figure I was given was on an oil boiler burning at 100% efficiency you can get 10.6kwh. Almost 19 litre of oil to heat the cylinder which would be about 13 euro.
These are the points that I found against the idea. I was told then if I insulated the house to a level that would drop the energy consumption that it might help my cause. But if you go so far on insulation why not go completely passive and do away with the whole plan.
If you do go ahead with it would it not be best to take the dhw out of this tank completely so you wouldnt have to achieve such high temps. I have found all in one heat pump cylinders which seem to be a good idea for dhw.
I also found something on parrafin wax cylinders from a site in Italy but the translation was rubbish but it seemed like an interesting way forward.