[len joburg]

Hi

I'm based in Johannesburg, South Africa. We live in the original Joburg farmhouse, which is a rambling structure with 600mm thick outer walls and 5m high ceilings. Above the celings is a cavernous attic (650m2) in which a person can stand up. The attic is topped off with a dark green corrugated iron roof.

In summer the attic gets uncomfortably hot and in winter it gets fairly warm - winter days in Joburg average around 20 to 22 degrees Celsius with most days being full sunshine. The attic temperature in winter gets significantly warmer than 22 degrees C.

A few rooms on the western side of the house get very cold in winter and I was thinking of cutting a hole (say 20cm diameter) into the ceiling of each of the cold rooms and installing bi-directional fans, which can blow warm air from the attic into the rooms in winter and warm air from the rooms, which also get pretty warm in summer, into the attic in summer.

Has anyone tried this before?
Given that the ceilings are 5m high, might this create a problem to heat the lower level of the rooms?

Am I missing something?
Any advice?

 

[Nealtw]

It is something to think about for the free heat in the winter but pumping moist air into the attic in the summer would be a problem here. We do everything to keep house air out of the attic. Than you also have a free path for fire.
If anything I would want a fan blowing cold air out of the room at floor level so air is sucked down but not replaced with house air.

Or maybe just a duct work around the attic so it could be seal and a fan to circulate it up and around. Then I would want the return at the floor level if you could .
With 16 ft ceiling a fan there might do more, I am sure it is warmer at the ceiling.



Let's see what others have to say.

 

[Bud9051]

Hi len and welcome to the forum.
Your weather and construction is a lot different from where I am in our cold country. We deal with the problems you describe with attic ventilation and insulation and air seal all paths between house and attic. As we look farther south we do often see whole house fans to exhaust warm air into the attic and out through attic ventilation.

Since you are in a predominately warm climate what you are thinking is probably possible. A concern might be if you climate includes very high humidity. Any air you exhaust out would be replaced by the warm humid outside air.

What is the material between house and attic, any insulation?

Is the attic open to the outside, effectively ventilated.

Bud

 

[dj3]

I have copper water pipes in the attic - the cold side in the shower is hotter than the hot side - for some 10 minutes - dropping my gas bill to less than $20 a month during the summer.

 

[udraft]

--------------------------------------- - winter days in Joburg average around 20 to 22 degrees Celsius---------------------------------?

That's 71° Fahrenheit. So I'm missing something. Is 20 degrees Celsius the same as 20C? (The word degrees is generally only used with Fahrenheit)
The idea of using that excess heat is intriguing, but can't say as I've ever heard of anything for that. Generally we're always concerned with keeping heat in the living space, venting out the unlivable space.

 

[Nealtw]

That's 71° Fahrenheit. So I'm missing something. Is 20 degrees Celsius the same as 20C? (The word degrees is generally only used with Fahrenheit)
The idea of using that excess heat is intriguing, but can't say as I've ever heard of anything for that. Generally we're always concerned with keeping heat in the living space, venting out the unlivable space.

yes 68 to 71F.

 

[len joburg]

Thanks for the comments thus far.

To address a couple of the issues raised thus far.

Our summer temperatures hover between in the 26 to 30 degree C range with some days between 30 - 33 degrees.

Humidity is not an issue in Johannesburg. Winters are crisp sunny days and very dry. It is a summer rainfall area. But even in summer, when the temperatures are high we have a low humidity with maybe a few muggy days.

Overall we have a very temperate climate. That said, as I mentioned before, the attic gets very hot in summer - the corrugated iron roof absorbs the heat, which the attic simply absorbs.

We don't have soffits in the attic - there are narrow gaps in the eves where air can move between the attic and the outside.

In terms of insulation between the rooms and the house - there are actually three ceilings. the upper two are timber - much like timber flooring and in many of the rooms there is also a pressed steel ceiling. So, the insulation comes by way of layers of air between the layers of ceiling.

The house was built in 1886, when gold was first discovered in the area - I guess attention wasn't paid to some of the finer point we consider nowadays.

That said, the temperature in most of the house is pretty easy to manage. It's just the few rooms on the western side that are a problem

 

[len joburg]

Yes, degrees Celicus is the same as C.

Apologies, In SA we have been metric since around 1960 and I have difficulty thinking if Deg F and feet and inches.

But if anyone wants to use imperial notation, I'll happily use a conversion calculator.

 

[udraft]

No problem, many of us are versed in metric and variable units of different sorts.
I couldn't get my head around "A few rooms on the western side of the house get very cold in winter". In your climate it seems you would never want to bring any of that heated attic air back into the living space. Sorry I have no useful ideas. You might look around the area at some newer expensive construction, see what they're doing.

 

[Bud9051]

Since the source of that heat is the sun, one of the best defenses would be a reflective coating on the roof. Many hot regions will paint their roofs white but there are even better options today. BUT that would also reduce the option of winter heat.

With basically no humidity issues venting house air into the attic is not a problem. You just need a lot of vent area for the attic air to escape. If a fan is blowing air in the passive opening for it to get out need to be larger.

Reversing the process to blow hot air from the attic into the house also needs to consider the air flow to replace attic air.

Bud

 

[len joburg]

Hi Bud

Thanks.

A major constraint - given that the house is the oldest house in Johannesburg, it is a national monument and I cannot change the roof colour.

The way the roof is fitted, there are a number of gaps where the corrugated iron sits on the walls - think sin wave - so there is no issue regarding attic air being replaced if I were to blow it into the rooms below.

I guess my main issue is how effective my idea might be. I.e. will blowing the warm air into the rooms from the attic warm the rooms, given that the ceilings are 5m high - I don't want to blow so hard as to create a wind storm in the room. In a sense, a person in the room should be unaware of the fact that air is being blown into it from the ceiling - i.e. it should not be discernable to people in the room, other for the fact that the room temperature is more comfortable, both in summer and particularly in winter.

 

[MTN REMODEL LLC]

I have copper water pipes in the attic - the cold side in the shower is hotter than the hot side - for some 10 minutes - dropping my gas bill to less than $20 a month during the summer.

Len....Interesting thoughts...somehow getting energy savings from a naturally occuring heat source.

Rather than a direct air exchange, wonder if there is a practical/efficient method of transfering the heat energy....sort of like solar pipeing....or similar in principle as DJ points out.....

IDK

 

[Bud9051]

Making the process effective and keeping the air flow below detection is definitely a conflict. My experience with high ceilings tells me there is already a lot of warm air up there. To move warm air down to people level will take a fan with some level of power and that can mean noise.

The modern appliance that moves heat from high to low without just blowing air is a heat pump. They work for both heating and cooling. I'm wondering if some combination that you can switch between seasons might do what you want.

Have to think on that.

And yes I was wondering about historic issues and you have them.

Bud

 

[SeniorSitizen]

Rather than attempting to force warm air down to a clod area in the winter, using PVC pipe build a water storage system in the attic of 2 or 3 inch pipe then pump the warm water down in the winter to cold room radiators with a circulating pump.



In the summer redirect that same attic pre- heated water storage to the water heater for use in appliances needing hot water. A few valves will be necessary to make the seasonal change and a drain valve for certain to drain the system if when necessary.

 

[len joburg]

Hi SeniorSitizen


Thanks for the suggestion, but I'm trying to keep things very simple and am reluctant to go your suggested route.


Bud, I'm thinking if I can just get some minor air currents going it might just work, But I guess I risk simply stirring the currents at the higher (just below ceiling) level, with nothing much happening at "ground" level. lain:

 

[Nealtw]

Rather than attempting to force warm air down to a clod area in the winter, using PVC pipe build a water storage system in the attic of 2 or 3 inch pipe then pump the warm water down in the winter to cold room radiators with a circulating pump.



In the summer redirect that same attic pre- heated water storage to the water heater for use in appliances needing hot water. A few valves will be necessary to make the seasonal change and a drain valve for certain to drain the system if when necessary.

Just like a heat pump .

 

[Bud9051]

A common approach to recover heat from a high ceiling is just a big ceiling fan. Noise and air movement would be under your control.

Otherwise a reversible whole house fan located in the ceiling is what you are describing.

Bud

 

[SeniorSitizen]

Hi SeniorSitizen


Thanks for the suggestion, but I'm trying to keep things very simple and am reluctant to go your suggested route.


Bud, I'm thinking if I can just get some minor air currents going it might just work, But I guess I risk simply stirring the currents at the higher (just below ceiling) level, with nothing much happening at "ground" level. lain:

Fair enough.
Please keep us informed how things work out.

 

[len joburg]

Thanks Bud - you may well be correct. Its just so cold down here on ground level, it's hard to imagine it could be warm up at ceiling level. Maybe even a small wall mounted fan could do it or even a fan mounted on a high step ladder to get the air circulating for test purposes.

 

[ron45]

I was thinking along the lines of SenoirSitizen but without the water.

Running a pipe through the attic that enters and exits in the room with a small fan to circulate the air inside the pipe might work. This way the air in the attic is not disturbed.

https://www.google.com/search?q=pip...pAhWOiOAKHTJiCssQsxh6BAgMECs&biw=1920&bih=937