Heating water for showers at my home in NW Ontario is expensive, in addition to the efforts I've already made to save electricity (LED lights wash/dry clothes after 10 PM, etc etc) I have just purchased one of these units and will install shortly. I have read extensively about the device and have looked long and hard in an effort to find someone who was using one and could share some thoughts about its "real life value". Despite it being a Canadian product I couldn't find one anywhere that could report on it....so I jumped in an bought one off the company website ($520 CDN) only $439.95 USD...ouch that lousy exchange rate hurts us Canucks :( I'll report back once its up and running...in the meantime has anyone here got one installed?

While you are upgrading, I'd investigate just how low you can go in terms of liters/min from the shower head. With plenty of pressure and the right shower head, I have no problem with using < 4 LPM - about 1/2 of the national average rate.

kenora - are you on a septic system or municipal wastewater?

My water comes from the lake and goes into a septic field

kenora - this is lifted from from an Alberta site but your temps won't be to different not to be concerned.

Drain line heat recovery Pipes
These are marvelous little devices that scrub the heat out of your shower water and transfer it to your incoming potable water just before it enters the hot water heater. This means that the water entering your hot water heater is 10 to 20 degrees warmer so your hot water heater does not have to work so hard. It also means that you can have an almost never ending shower because you are unlikely to run out of hot water. This has to be good right? Well, let’s think about that before we rush out and buy one.
If you live with a septic treatment system, you need to know the impact it will have on the system. To understand the effect it will have on the system, you need to understand a bit about how your septic tank works in our colder climate.
Understand that the base soil temperature in much of Alberta is under 43º F (7ºC). In the winter, the first 8 feet will be anywhere from -20 (-28) to 36 (2)º. Which means that in the winter, your septic tank will be surrounded by a temperature quite a bit lower then the 43º base soil temperature.
By the end of a winter night, the bacteria and other microbes we rely on to break down the sewage will have gone mostly dormant, with some still working slowly and others killed off. When the family gets up in the morning, they tend to use the facilities and the shower. Now the tank gets enough warm water to raise the temperature enough that the microbes wake up and start digesting the sewage. As well, you have supplied them with fresh food. As they start their work, they also start reproducing. All this activity raises the temperature of the sewage a bit more, so they start working and reproducing even more. Now you have a whole crew of hard working microbes breaking down the sewage just because you warmed them up a bit. Slowly this activity will slow down, due both to lack of fresh food and declining temperatures (heat loss to the outside), so eventually the microbes go dormant again until you restart the cycle.
Now imagine that you deprive the microbes of the rise in temperature. The may react a bit to the fresh food but not very much. Without the warmth of the shower water, you will not get the spike in activity. Without the spike in activity, the actual sewage temperature will drop even closer to the surrounding soil temps. This is part of the reason some tank in low use systems freeze up during the winter, while others that are supported by a three or five person family will do just fine.
It is not only the risk of freeze up that you have to be concerned about. When there is little microbe activity, the sludge layer builds up. More importantly, the suspended solids in the middle portion of the liquor are not being digested so the next time you flush a toilet or drain a sink, you are forcing these suspended solids on into the dose tank, which is even colder. From there they go out to the field where they seal up the soil pores and start building up the bio mat layer which of course eventually leads to failure of the field.
So really, you need to decide if the few heating dollars you save are worth shortening the life of your septic treatment system.

Since you already have the HX - let the grass grow taller or mulch and don't disturb the snow over the septic tank to make up for the BTU loss. Ie, insulate vs deliberately sending heat out of the house. Maybe cut back on things that kill/inhibit bacteria or on total water usage.

Sounds serious! I hope the septic system doesn't suffer as a result... Mind you we still have the almost daily clothes washing... But that's in either cold or warm water. Never hot!
I realise I am cooling the field a few degrees using the hx and will now have to think of a strategy to keep it warm. It seems there are pitfalls to every strategy.

So how much did it cost you to install the septic system?

I've been thinking about this scenario...
It seems to me that cooling the shower water a few degrees can't possibly be as bad as you think... There are days..sometimes weeks in the dead of winter that my wife and I are away from the house and no water hot or otherwise enters the field.
There are also periods (weekends and holidays) when there are 5 or more showers a day along with several sink loads of hot water from hand washing dishes as well as the occasional warm or hot water clothes wash from guests.
With these dramic opposite usage cycles at my home during cold weather considerable stress is a reality that I can't change.
I think I will increase the pump out cycle from 4 years to...... 3 or maybe 2... to keep the solids under control.
Additionally since I will be renovating the house and excavting near the 1000 gallon septic tank anyway I will take the opportunity to expose the tank add some rigid foam ontop and along the sides to keep the heat of digestion in the tank longer....

any thoughts?

I think that insulating the tank a little bit will more than make up for the BTU loss (which may not create a problem anyway). Note that the concerns are an "arm chair experiment" - there are no supporting data or links.

Sticking a temperature probe in the septic tank and logging before and after results would be quite interesting.

Posted By jonr on 29 Nov 2015 11:22 AM
Sticking a temperature probe in the septic tank and logging before and after results would be quite interesting.

Hummmm.... gonna give that some thought :/ :) thanks for getting me thinking about it though

The whole notion that by using drainwater heat recovery you won't be injecting sufficient BTUs into the septic tank for it to operate is not well founded. The outgoing water temp will be above that of the incoming water, and well above the deep subsoil temperatures in a Kenora location, especially at the modest recovery efficiency of the A1000.

I have a 4" x 48" PowerPipe installed at my house, which is a gravity-film type, unlike the horizontally mounted A1000. During an extended shower the output of the unit measures about 22-23C when the incoming water is 3-4C. The A1000 isn't nearly that efficient, especially when mounted horizontally. The more steeply you can mount it the higher the return efficiency as discussed in this blog bit:

http://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/drainwater-heat-recovery-comes-age

The point is not the average temperature in the tank. The issue is creating temperature spikes to create a feeding frenzy which further increase or maintains a higher temperature. Fly wheel effect.
While it is indeed true that warmer temperatures have higher microbe activity rates, that is not the issue here. The microbes in any given tank a uniquely suited to that temperature range. If the temperature increase or decrease any significant amount, these microbes die off and are replace by those suited to the new temperate range.
If this change is sudden, the tank colony can die off and it may take hours, days or months to reestablish health levels.

By early morning, the tank is at its coldest. Feeding has slowed down and temperatures have bleed off. The microbes are at the low end of their happy scale so are doing very little work. As warmer waters and fresh food is added during the morning rush hour, activity ramps up. It takes a lot of btu's to raise the temps in the tank enough to create a real feeding frenzy so any that you rob are detrimental to the overall performance. The primary food for the microbes are the suspended solids in the liquor. These are the most important to remove from the waste water stream. The more tss that escape the primary tank, the shorter the life of the downstream soils based treatment facility.

Yes, it might help to pump the tank more often. Around here, the suck truck charges between $250.00 and $650.00 per services depending on how far from the disposal site you are. That might effect the ROI on the EcoDrain. Also the need to pump a tank always reflects some abuse of the system. If you religiously only put bodily byproducts and water (in the right ratio) into the system, you won't have to suck the tank.

Insulating is always a good thing so we won't charge that to the ROI.

Septic systems have become much more expensive in recent years. I have not reviewed the Ontario regs in a while, but they use to be even more restrictive then Alberta's. Many lake shore communities have even more restrictive codes to deal with.
In the last couple of years the least costly system I designed and installed was for a three bedroom with almost perfect soils. $18,000.00. The most costly, a 7 bedroom with really bad soils and seasonal saturation, near surface. $67,000.00. Oh and that does not cover the $2,500.00 design costs. The point I am trying to make is that septic systems are expensive. Only the owner can decide how long they will last so look after them! or not, I'm okay either way. I'm sure my colleague in Ontario need to make a living too.

This whole scenario reminds me of the young fella who over chipped his pick em up truck to shave one second off his 0 to 60. And he did! Next month he dropped $13,000.00 on a new engine.

And, when you're dumping in water that's above room temp during a shower out the bottom end of a A1000, it's quite a bit warmer than the water in the tank- it's definitely a spike in temp, just not as high a spike as if it were getting ~35-38C water directly from the shower drain.

The A1000 isn't even half as effective at stripping the heat as an 8' long 4" diameter gravity-film type (north of 80% energy recovery @ 2.5gpm) unless you mount it pitched at a 75 degree angle, at which it's about half as effective, or 45% per the manual: https://ecodrain.ca/media/products/ecodrain-installation-manual.pdf . Most installations of that unit are probably in the 35% recovery range. Water coming in at 2C, and headed down the drain at 38C (a 36C delta) leaves the house at about 25C which may be a bit tepid, but it's not cold. The difference in total BTU going into the tank during the shower is the difference between a low-flow shower head and a full-flow shower head. Is a low-flow shower head going to cause the biota in the tank to crash? Methinks not, but if you could show some actual in situ real-house DATA on it I could be convinced.

You may be right that this model only reduces the btus going to the septic tank by 30% but please consider that is of the 40 to 60% already reduced by switching to the low flow shower head in the first place. In today's world, other than a dishwasher, the shower is the only device sending heated water to the septic (unless you are a tub person in which case this discussion is moot.) The dishwasher doesn't even create a net positive to the system due to its toxicity.

Septic systems seldom die catastrophic deaths (and these are usually the easiest to fix), they die a little at a time. Constant use of cleaning products, grease or water softeners. Doing all your laundry in one day, using the wrong laundry chemicals, etc. These all send more suspended solids out to the soil based facilities clogging and killing them. And now you want to take away more of the one thing that helps them survive.

At the risk of twisting your words, then the 8' long gravity film units are terrible for the system.

I have yet to see any data that indicates than even a house with no water heater (say they shower at the gym, always eat out and only wash clothes on cold) causes a PROBLEM (vs just slowing biological activity by some unspecified amount ). I see a few references to sporadically used systems (like cabins) freezing (but that's not what we are talking about).

Perhaps problems will occur as energy waste decreases. But I suspect there will be solutions other than dumping heat down the drain. For example, multi-chamber, insulated septic tanks than can optionally be operated in a mildly aerobic mode over the Winter.

Jon - that is sort of like saying " I have yet to see any data that people without legs can't walk"

If you have done any searching at all, you will have found mega technical data on the growth and reproduction of various microbes. Studies such as

http://textbookofbacteriology.net/nutgro_5.html

Here you see the relative narrow range of temperatures for various bacteria. Can we expect bacteria in a septic tank to behave similair to bacteria in other environs?
Have you ever maintained a compost pile?

It was not my intent to give lessons on septic design and maintenance on this thread. However a few bits.
Yes, aerobic environs are much better then anaerobic. Where do you get the air from on a 40 below winter day? That is the failing of many ATU. Some do use internal air for this purpose.

When we discuss septic problems or failures, we can divide them into two categories. The first we can call catastrophic failures and the second time phase failures.
In the first group we see failures related to dumping a gallon of bleach or other toxic substance into the system. Also things like pump or aerator failures. Of course we would include tank collapse or mechanical disruption of any part of the system.

In the second category we see the slow death of the soils base facility. It always results because of a build up of bio mat which first plugs the soil pores and secondly block the facility itself. Ever have the pleasure of digging up a failed system? Lots of thick slime. This is bio mat. Now we need to find out why the bio mat formed. In some cases, it is the problem of the field itself. Poor overland drainage design causing flooding of the field. Seasonal saturation causing ponding to occur in the trenches or the mound. However, most failures are because to much suspend solids make their way out to the field, strangling it to death.

When we look at the causes of too much tss (total suspended solids), they generally fall into two categories, overload or to little digestion. Overload is caused by poor design, that is not matching the tank size to the daily peak volumes, or using to much water at once, such as doing all your laundry on one day rather then spreading it over the week. Overload causes the sewage to be swept along the system without time for stratification of the solids and fog or the digestion of the sewage in the primary tank. This forces these bits straight out to the soils based facility where they are added to the already present bio mat. When this happens often enough, failure!
Too little digestion can also be a result of poor design, that is as mentioned, lack of residency time. This usually happens early in the life of the system or when some major change occurs, the kids and the grand kids move back in! When failure comes later in the life of the system, it is usually because of a weak colony of bacteria. The colony can be weak due to several different causes but a major one is the lack of optimum temperatures and temperature spikes. This is much more prominent in colder climates. As mentioned, warmer environs always produce greater activity, so those of us living in these colder climes are much more cognizant of giving totally good care to our systems.

So no, I can't give you a study with data that shows the shower significancy on the septage. I am giving you the results of more then forty years of designing and installing systems from Ontario to Alberta. And more importantly, fixing failed ones. I can show you how much harder it is to keep a commercial (office) system functioning properly then it is to keep a residential system of the same daily flows functioning properly. The only real difference is longer quiet times at night and no showers for the office flows.

Don't know if any of this will help you but it might helps someone who truly needs to know.

A cold climate septic tank system at a household that only showered (never tub-bathed) and had a 4" x 96" PowerPipe, and only washed hands & clothes in cold water and used an energy-miserly dishwasher could have some issues, but that's a pretty silly argument to be make, since that's not how most people live.

Even flushing the toilet with water at room temp gives it a bit of a BTU bump, maybe even more than a 6 minute low-flow shower at the 80%+ recovery efficiency of that bigass 8-foot heat exchanger (that wouldn't even fit in most houses, BTW. The biggest they make is a 4" x 120"- a ten-footer!) But at the ~50-55% recovery efficiency of a 3" x 60" or 4" x 48" I doubt it's an issue. At only mid-50s heat recovery it's still a LOT more heat in one 10 gallon lump than the non-bathing commercial office system example, some of which fail, many of which do not. And at the modest recovery efficiency of the A1000 it's in the statistical noise of how real households use hot water.

Canada has more drainwater heat recovery heat exchangers installed than the rest of the world combined, if the concentration of drainwater heat recovery manufacturers in than nation is any indication. (Are there any non-Canadian residential drainwater heat recovery manufacturers out there yet ( other than GFX/WaterFilm Energy Inc in the US, that is)? I expect if it's REALLY a problem for septic systems we should be able to find at least a few real-world examples by now.

Retherm seems to be in denial of even a remote chance of it becoming a problem, per FAQ # 6:

http://www.retherm.com/ReThermFAQ.htm

Here is a worksheet that puts some numbers on septic tank inspection frequency (which IMO should relate to biological activity/septic tank health) in a cold climate. Oddly enough, low flow showers and less washing machine water REDUCE risk and lengthen inspection intervals (less flow = more time spent in the tank and more time for solids reduction).

Similar results when looking at specs for commercial septic systems or septic systems in Alaska. Ie, much concern about gallons per day vs tank size, NONE about cooler water going down the drain.

So here's my hypothesis without data: install lower flow shower heads at the same time as the EcoDrain and your septic tank health will increase. So slightly less frequent pump outs and even more $ savings.

Not sure what to believe? Then inspect more frequently and pump as needed.

Dana -
"The dishwasher doesn't even create a net positive to the system due to its toxicity." There is no doubt dish washers add hot water to the wastewater flow. Unfortunately, due to the chemicals used, they do more harm to the colony then they do good. And yes, they use less water then hand washing.

Only the first flush and maybe the next half of the morning and evening rush hour will be near room temperature, the subsequent ones will be at incoming potable temps. And then that is only 1.6 gallons these days. So other then showers/bathing, where does hot water enter the flow?
Office systems should never fail, they have to be designed differently to account for the lack of bath water.

Just because some jurisdictions hand out more R&D grants, that has nothing to do with the amount of product making it to market, right? And please remember that the largest part of the Canadian population lives in areas with higher design temps the Minneapolis.
If so little energy is extracted, why bother putting them in at all? How many waste water heat recovery units are more then five years old? How many of those are installed in the country compared to the city? Do we have any numbers? As I have been saying, wwhr unit will not cause catastrophic failures, they just shorten the life of very expensive systems.

Would you really expect ReTherm to say any different? I didn't see them offering any replacement costs warrantees if the septic did fail.

BTW - the boys and girls in Ottawa only tested for the actual heat transfer between wastewater stream and the potable water stream. They did nothing about stand by losses or theft of heat from the house it self.

Jon - you would do better to go to some site that teach how to design, or better yet, take the course, rather then spend all day searching for red herrings. The info you list is from 09, right near the end of "less is always better" era. So their thought (and the thought of some still today) is that if you use more, you need to pump more. The truth is that in the last five years, many jurisdictions have dropped the daily peak flows per person used to calculate system design, from over 150 gallons down to in some cases under 50 gallons. Yet at the same time, they are increasing the average CBOD5, TSS and FOG that has to be treated. It just means we have higher strength waste water to treat rather then higher volumes. Higher strength when it comes to residential waste is always a higher ratio of solids to water. Because there is more solids, it requires much more biological activity to digest which does not happen proportionally. Therefore we get faster rates of sludge build ups. If the new codes did not account for this, systems with low flow everything would require MORE often pumping. To offset this trend, the new codes require bigger tanks with room for more sludge. Now you can still pump every three to five years in spite of the fact that the low flows have made matters worse.

Almost all the documents you would have found where written at a time and by people who would not even have though that anyone would be so misguided as to steal heat from a septic system ;-) https://nextcity.org/daily/entry/water-conservation-problem-broken-sewer-pipes You can find a number of articles like this showing how reduced water flows are creating problems. It turns out most cities are using tons of potable water to flush these lines to move the stagnated sewage down the pipe.