Go Bottom

holding tanks

View my Photos
TomG
Join Date: Feb 2002
Posts: 5406 Upper Ottawa Valley
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2002-04-18          37574


I've got an idea and want to see how it sounds. First, I seem to have a serious case of distraction this morning. I did proof read my other posts and still butchered a bunch of grammar. Sorry. My spell checker just informed me that I had misspelled ‘grammar’ as well. Tough morning!

The plumbing question is whether anybody has heard of a holding tank installed in the feed line to a hot water heater. The idea is to save electricity (in my case) by allowing well water to warm up in the house before if goes to the water heater. Some friends thought their oil water heater was coming on about every time hot water was used, and a holding tank was a plumber's solution. They say it noticeably cut their oil bills.

However, I'm not sure how efficient heat transfer from a conventional tank directly to air would be. I have looked around the net and found various specific heat exchangers designed for flowing water, which are also very expensive. I've been wondering if a set of 1" thin walled copper pipes with air space around them and standing vertically might work better. I figured that 6' of 1" pipe holds about a gallon. However, I'm not sure if a base and top for such a thing is available, and I'm not sure how to go about constructing one. It would end up weighing quite a bit, and depending on solder joints doesn’t seem a good idea.




Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



holding tanks

View my Photos
DRankin
Join Date: Jan 2000
Posts: 5116 Northern Nevada
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2002-04-18          37586


Tom, I am reminded of the free lunch deal. If you bring a tank of cold water into your home the BTU's to warm it has to come from somewhere. Do your have a solar heated room? I have worked with heat exchangers in the past. I hear that your water heater is electric. How do you heat your house? ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



holding tanks

View my Photos
cutter
Join Date: Feb 2000
Posts: 1307 The South Shore of Lake Ontario, New York
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2002-04-18          37607


I have seen all sorts of devices. One guy had a stacked version of the 55 gallon drum stove kit in his basement. Nothing combustable around them, but I wouldn't have wanted the thing in my house. He did what I have seen others do in the winter and that is to run Cu coils around the stove to heat water. Solar works well if you receive enough sun, we don't up here. Despite that, I have seen a number of water heaters on the roof or stand alone built from black PE or PVC, primarily to heat in-ground pools. In my area, we are offered time-of-use electric meters that have an off-peak rate of around 5 cents a kwh. I bought an 80 gallon energy saver electric hot water heater and timed it to run strictly during the off-peak hours. No fire to tend or cloudy days to contend with. Heats well too! ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



holding tanks

View my Photos
TomG
Join Date: Feb 2002
Posts: 5406 Upper Ottawa Valley
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2002-04-19          37617


I have no solar, active heat exchange or wood furnaces in use. I've looked a bit and thought about a combination of solar and heat recovery from waste water. The equipment to do it seems pretty expensive and I wonder how long it would take to get the investment back. Of course our electrical rates are exploding, so maybe the answer is 'pretty quick.'

What's in my mind is a simple passive system. Get enough water in the basement and it would stay around long enough to warm up before triggering the electric heater. True enough that the basement would be cooler, but I'd just as soon it was for most of the year anyway. It also probably continues to get some ground heat throughout the winter. The house is heated by oil. At the moment it is cheaper than electricity by quite a bit, so I wouldn't mind if the furnace came on more often if it was keeping the electric water heater off.

However, maybe this 'do it yourself energy efficiency' isn't all that practical. Maybe Cutter's comment about a new water heater is the way to go. At the moment, I have a 'nothing special' heater wrapped with 6" fiberglass bats and covered with vapour barrier. It should at least store heat fairly efficiently. I guess I could put a loop in the output pipe. The idea is that hot water rises, so it comes up the output pipe and continues along horizontal runs until it cools. A loop in the vertical output pipe forces water flow back down and contains circulation of the hot water. I did that in another house, but it’s difficult to tell how much difference it made.
....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



holding tanks

View my Photos
Peters
Join Date: Feb 2002
Posts: 3034 Northern AL
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2002-04-19          37629


Tom;
The water from the well should be at ground temperature, therefore no heat savings from the basement.
I have a ground based heat pump which is hooked to an unheated 50 gal second tank. The heat pump heats the water to 120 when it is running. I like this system.
I built a heat exchanger quite cheaply using the stainless steel flexible connectors and PVC pipe. I can heat the pool using the outside wood burning stove and the exchanger.
Your problem is the heat source. ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



holding tanks

View my Photos
Murf
Join Date: Dec 1999
Posts: 7249 Toronto Area, Ontario, Canada
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2002-04-19          37634


Tom, just off the top of my head I would have to say that it would probably cost you more to put together some system to pre-warm the water than you would save on the water heater's reduced consumption, or at least the payback would probably take more than the life expectancy of the system. Best of luck. ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



holding tanks

View my Photos
DRankin
Join Date: Jan 2000
Posts: 5116 Northern Nevada
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2002-04-19          37638


Tom I wondered if you had an oil fired boiler and baseboard heat. If you do there is a real nifty heat exchanger on the market that fits into the water tank and provides a nearly inexhaustible hot water supply. Several of my friends in Alaska had these units installed and swore by them (rather than at them) for convenience and costs saving. ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



holding tanks

View my Photos
Peters
Join Date: Feb 2002
Posts: 3034 Northern AL
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2002-04-19          37642


In the geothermal system the cost of heating and cooling a 4000 sq ft house and providing hot water is approximately 50$ per month. With a conventional system the cost for hot water is 50$ and at least another 100$ per month to heat and cool. It cost me approximately 3.5 K extra not counting my time, therefore the payback is 3 years.
The crux is I am down to needed less than 700 watt hours. At current prices it would cost me about 10K for solar panels to disconnect from the grid. Now if the cost of the panels can just decrease to make it pay back in 3-5 years!!! ....


Link:   Solar system

 

Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



holding tanks

View my Photos
TomG
Join Date: Feb 2002
Posts: 5406 Upper Ottawa Valley
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2002-04-20          37666


Thanks for the comments. There's a couple people around here who have wood furnace boilers that heat both the house and provide hot water. That's probably similar to the Alaska rigs. I've heard some pretty good things about them. I've also heard that wood furnaces are real wood burners compared to modern wood stoves. Unfortunately, there's nothing to work with, because we've got a typical oil burner forced air system.

Yep, the connection between basement and ground water temperatures is one I wouldn't have thought of. Perhaps I should have since I had an experience at my father's place in Lake Havasu City, AZ. The city water gets so hot just flowing through the system during the summer that many people turn off their water heaters and keep a jug of drinking water in the fridge. Nobody told me, and I took a somewhat extended shower, and spent most of the time trying to adjust the water.

A lot to be said for the idea of ground heat. I do think our basement gains heat from the outside during the summer and the furnace during the winter. At least we lightly insulated the pressure tank and some of the inside pipes to reduce condensation during the summer. Sort of ironic now because the condensation cure adds to the costs of hot water.

Like Murf says, if I cost anything that will make a significant difference out, I may find very long payback times. But then, it's a little hard to forecast future electric and oil rates. Don't know, but the deep well water is really quite cold here, and our friends thought a holding tank made a difference for them. However, their problem may be more related to the particular oil water heater. The problem was that it came on frequently after using only small amounts of water. Maybe the thermostat is located close to the water intake. I don't know how much heat goes up the chimney after each burn on a water heater.


....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



holding tanks

View my Photos
Murf
Join Date: Dec 1999
Posts: 7249 Toronto Area, Ontario, Canada
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2002-04-22          37701


Tom, a couple of quick(?) items that occurred to me afterwards, of course, sorry it didn't come to mind when replying originally. First if you have forced air type heating, hot water supplement is easy, they have coils that you install in your furnace's plenum sort of like a central air conditioner runs. Further to that idea, check out the link below, these stoves perform exactly as advertised, I have had several for years now, they were invented and built by a local here until recently when he retired & sold the business, they are not expensive, especially compared to those outdoor furnaces. Finally, there is a fellow in Manitoba who sells a 'how to' kit (that works, I tried it) to convert ANY oil burner to run used moter oil, etc. If I can find his name, etc., I will pass it on to you. Best of luck. ....


Link:   Sedore Multi-fuel Stoves

 

Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



holding tanks

View my Photos
Dan Bessette
Join Date:
Posts: 1
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2002-04-22          37710


Tom,
Just a thought, but it might help. How hot does you water get and have you checked your mixing valve lately. I was having trouble with hot water and running out too quickly. I adjusted the mixing valve and since the water has been hotter (not too hot) and we don't run out. In my case we have some silt in the water so the valve had gotten plugged up. It is also possible that you are getting too much cold water mixed back in with the hot water from the boiler. This would waste hot water quickly. A simple thermometer check would tell what temp your hot water is.

Good luck ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



holding tanks

View my Photos
TomG
Join Date: Feb 2002
Posts: 5406 Upper Ottawa Valley
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2002-04-23          37731


Mostly I'm just starting to react to rapid increases in electrical rates by thinking of ways to improve efficiency. Things work OK and there's enough hot water. We keep it not especially hot, and with the extra fiber glass bats around the tank we can still turn off the heater for several days and come back to a hot shower.

I think my alternatives are: a better heater; different fuel; or waste heat recovery. I think of the original passive holding tank idea as one that would take extra heat out of the basement mostly generated by solar load or oil furnace operation. It's mostly an alternative fuel idea.

A coil around the furnace probably is a more active version of the alternative fuel idea. It would be tempting to use the flue pipe, but our medium efficiency furnace already takes enough energy out the flue gases that the top of the chimney builds up frost during very cold weather. That's a problem in it's own right.

A wood fired supplement seems like a pretty good idea, and wood can be cheap here. Outdoor wood furnaces are expensive but insurance companies like them. My brother in law recently installed a second wood stove. His insurance company has a list of approved stoves and wanted to inspect the installation themselves. Our own stove bit the dust when we discovered the chimney had to be replaced. The cost of running a new outside chimney from the basement to above the roofline wasn't a pretty penny, and stoves in basements don’t work that well anyway.

I wonder if Sedora stove is what some friends bought a few years ago. He described the stove as designed so it re-burns flue gases. Whether its the same design or not, he really likes the stove. I don't know how the addition of heat exchangers to do something like heat water might effect the efficiency of these fancy stoves.
....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



holding tanks

View my Photos
Peters
Join Date: Feb 2002
Posts: 3034 Northern AL
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2002-04-23          37739


One of the small things that you can do to improve efficiency is to have the hot water water inlet exchange with the outlet on the shower.
Although I ran the house in PEX (crosslinked polyethylene) we spliced in a coil of copper around the shower drain pipe. This allows the inlet water to pick up some of the waste heat flowing out of the shower.
Naturally this requires two this, access to the shower drain in the basement and constant use of the shower. ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



holding tanks

View my Photos
MikeB
Join Date: Oct 2003
Posts: 37 CT
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2002-04-23          37742


Ahhh!!!!!!thermo dynamics. I had a stepson who was taking this class at purdue.....it drove him nuts!!!! He passed. I fondly remember helping him....it was one of the first times he and I really put our heads together. I had no formal education, but had alot of expeirience with refrigeation and also accurately metering anhydrous ammonia in corn fields. but him and I pulled it off.
One of the first things I realized about thermo dynamics was the fact that every bet is hedged and there are never any really clear cut answers. I know...this gives you no advice...this is just a thank you for helping me remember some of the best days of my life. ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



holding tanks

View my Photos
TomG
Join Date: Feb 2002
Posts: 5406 Upper Ottawa Valley
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2002-04-24          37769


I did find a commercial heat exchange product for shower drains a few years ago. I think it's is called GFX something or another. I checked my bookmark but the page isn't on the net any longer.

As I recall, the product needs a minimum 5' vertical drop between the shower and drain. The unit appeared to be a fairly large diameter vertical copper pipe with standard water pipe coiled along its length. Info on the site said that efficiency of the unit is due to the fact that waste water going down the vertical will swirl around the inside surface thus improving the heat exchange. There also was an explanation that the unit is more efficient if it's installed in the main water feed rather than the water heater feed line. There was an explanation, but I never understood the logic.

I never became too interested in the product because our shower is shower and water heater are in a shallow part of the basement where there isn't 5' clearance above the drain. I also figured that I'd have to talk my wife into taking showers rather than baths for the idea to be worthwhile. I believe I'd rather pay the electrical bills.

I also thought about holding tanks for gray-water and active exchangers but I never got past the cost of the equipment.
....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo


   Go Top


Share This







Member Login