waste water heat recovery, anyone use it?

[Northern Mike]

I have been looking at this stuff for a while now, but could not capitalize on it at my old house.

My current house (we just moved in about two months ago) I believe could be a good candidate for this type of equipment. The current house as a totally unfinished basement (so access to everything), where the other place was completely finished and a lot of work to get at the piping.

Has anyone used this stuff and or noticed any benefit with it?
I'm now on an electric hotwater tank so I am looking at this again being electricity is a lot more expensive then natural gas (which is not available in this area.

[Bud9051]

Hi Mike,
I have read a bit in the past, but I basically decided I will eventually go solar, even though I'm on the Canadian border. However, there are some rather simple approaches to grey water heat recovery and it might have some numbers to make it worth while. In my case. if I install a solar heating system, then my hot water will be so inexpensive that recovering waste heat is not economical.
Here is a link to some options.
Solar Water Heating Projects and Plans

Bud

[Northern Mike]

Although you probably see slightly warmer tempuratures then I would during the winter months, I am definately interested to hear how well that system works.
I've been eyeing that type of system for some time, but wondered how it would fair here during the winter months. We do get at least one week (some years up to a month) of colder then -35'C tempuratures during the winter.
I know a few people that use these systems for heating their pool water during the summer, but I can't say I know anyone (locally anyway) that has used this for pottable water.

[Bud9051]

You are considerably colder than central Maine, as a steady 0°C would be our cold spell, but that's not taking into account the shift to warmer temps we are seeing, which I'm enjoying but not relying on. But there is another factor that goes with our cold temps and that is a very cold starting temp for our hot water. My out of the ground temps average around 45°F and drop to 35°F curing our cold spells. With a thermal storage tank in front of my electric water heater I can at least take the edge off of winter water heating and probably handle 80% of the other 9 months.

I'm currently renovating the entire house so my opportunity to play with solar hot water will have to wait, but the project will give me some first hand experience to help others and look at what can be done for total home heating. So, for now, no specific design in mind, just a nice south facing garage roof that keeps calling my name.

The first step is always to reduce your demand, low flow shower heads and getting the kids to grow up and move out. Once my two daughters moved out on their own my electric bills dropped $100 a month. With just the wife and myself, our use is low, thus the savings would be minimal. But it would be fun to play with.

Bud

[Northern Mike]

You sound a little like myself. I'm currently eyeing my soon to be built new garage south facing roof for potentially solar power. It's current design (I'm sure I'll change a few things before we build) is a 32'x36' garage with a perfectly unobstructed south view from the roof.

Anyway... back on topic.
Our water usage (hot anyway) is currently pretty low. Family of 4 with two young boys (9months and almost 3), our hot water usage for showers/baths are not as bad as they will get when the boys get older (I have a long way until they move out). Laundry is done with cold water and the only other real hot water usage is for dishes (by hand and by the dishwasher).
All facets (except the kitchen) have been changed over to low flow. Water and sewer costs was almost as much as our electrical bill when we lived in town (much smaller house), so we are fairly accustom to saving water where we can. Being on a well now, non-heated pottable water is not much of an issue, but I still am keeping up with conserving (saves me having to fix the equipment).

One advantange I may have over your setup is that my preasure tank for the well pump will warm the water a bit, plus it's within ~10ft of my boiler, so the tank itself will generally bring the water up near room temp. I have not borrowed my office's lazer thermometer yet, so I can't give exact numbers.

One of the reasons I was looking at this power-pipe arrangement is that I am not affected (directly) by the outside temp. With the solar heat, I have to worry about the extreme cold days and when the hotwater is actually in demand. I'm showered and out of the house before 5:45AM, and the boy's bath time is generally before bed (after dark most of the year).

The one kicker with the power-pipe product is the way my waste water us run from the primary locations using hot water. The gray water from the upstairs bathrooms comes down from one end of the house, and connects (via tee) to the waste water from the kitchen. The tee is pretty close to where it exits the house, so I would need to either run two seporate pieces (expensive and not as efficient) or adjust the pipe work a bit to accomidate a single length of this product.

[Bud9051]

Just helped my son build his 30' by 36' garage, I supervised and was the ground level gopher.

I have run a power meter on a few electric hot water heaters and they haven't been as bad as I would have estimated. We are around $0.17 a KW and at your use I would expect about $24 a month. Some of that would be stand-by and pipe loss so even if you recovered 1/3 of the waste heat you would be looking at $8 a month. A full electric inventory isn't that hard to do and it will point to potential savings. Canada is pretty progressive so you might be able to find a 220v power meter to get a reading.

Passive recovery is actually not that effective since once you have some heat recovered your ability to recover more goes down.

Bud

[drooplug]

Boiler? What type of fuel?

Pipe a heat trap onto your tank to help stop gravity flow from sucking energy out of it. http://comfort-calc.net/Indirect_Piping.html

[Northern Mike]

Boiler? What type of fuel?

Pipe a heat trap onto your tank to help stop gravity flow from sucking energy out of it. http://comfort-calc.net/Indirect_Piping.html

The boiler is oil heated.

Unfortunately I don't have time at the moment to read the link you posted. Could you explain a bit more of this heat trap and which tank you are refering too?

[drooplug]

I am referring to your hot water heater. A picture is worth a thousand words so go to that link and look at the picture.

You have the option to add an indirect water heater to your boiler. I'm not sure if it will be cheaper than electric though. Perhaps someone else could weigh in on that.

[Northern Mike]

You have the option to add an indirect water heater to your boiler. I'm not sure if it will be cheaper than electric though. Perhaps someone else could weigh in on that.

I have been thinking about doing that as well, but the cost of fuel and the current amount my boiler is consuming is crazy. I am going to be getting the boiler some major TLC soon as it hasn't seen any maintenance in ~3 years (as per the local service guy). From what I have seen from the rest of the house, I have no reason not to believe that.

Once I get the boiler straightened away, I think this might be a good idea.
I will be enclosing the untilities (heat, water, laundry) into a room soon, which should help as well. Currently everything is in the corner of our 100% unfinished basement which sees a lot of lost heat with the bare concrete walls and floor.

[Bud9051]

Isolating your combustion appliances will still require that you provide an appropriate amount of combustion air and that can often seem like a lot. It also doesn't reduce the stack effect that pushes the cold air into your basement and thus the warmer air up and out the upper portions of your home. Air sealing is often referred to as the best first step for reducing heat loss and certainly one that should be done before extra insulation covers those areas.

Here is an efficiency Vermont web site that details where air leaks can be located.
http://www.efficiencyvermont.com/ste...ide_062507.pdf

Bud

[Northern Mike]

Isolating your combustion appliances will still require that you provide an appropriate amount of combustion air and that can often seem like a lot. It also doesn't reduce the stack effect that pushes the cold air into your basement and thus the warmer air up and out the upper portions of your home. Air sealing is often referred to as the best first step for reducing heat loss and certainly one that should be done before extra insulation covers those areas.

Here is an efficiency Vermont web site that details where air leaks can be located.
http://www.efficiencyvermont.com/ste...ide_062507.pdf

Bud

I have a thread about the utility room here Brand new basement utility room
In short, after a quick bit of measurements, it'll be about 12'x18', with vents on the west and north wall.

Anyway, this has gone off topic.