GFX vs home brew

Page 3 of 5  
snipped-for-privacy@ece.villanova.edu wrote:

At some point the water needs to be heated to about 140F to kill bacteria before use in showers and baths.
I fail to see the point of all this pumping and mixing between hot and cold sources. What do we gain by this??
Bronze Taco pumps are cheap and use less than 100W to move 10+Gal/Hr to 15 feet or more.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

No it doesnt.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Rod Speed wrote:

Do a little research and you will find that Canada HAS such a spec. Read about it today searching for the valve (Tempering Valve) that mixes hot water with cold to prevent scalding. Their spec says that hot water heaters must attain a temp of at least 60C (about 140F) in order to kill this bacteria, and that water heaters can frequently output 75C water (about 167F) Scalding occurs (and I was a victim of this at about age 4) most often in households that draw a bath using solely Hot water, then temper with cold to get the desired temp. I was impatient to get my bath that night, and due to the arrangement of water controls and my size, I could not reach the cold water control without climbing around the lip of the tub. Needless to ay, I slipped and dropped my foot into the HOT water. My ankle bone was VISIBLE thru the skin for several days after that.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

More fool canada. You cant ignore chlorination.

Separate matter entirely.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Rod Speed wrote:

Not Canada, Australia has the spec
http://www.dux.com.au/tech_domestictemp.htm
Read this page, it describes EXACTLY what happened to me at 4 years of age, why hot water heaters have this spec and why tempering valves can be a valuable addition to homes with either very your children or the elderly.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Irrelevant to what is being discussed, whether water MUST be heated to over 140F to kill bacteria. That clearly isnt necessary if the water is chlorinated town supply and the water isnt stored on site before use.
We dont bother to heat the cold water to over 140F before using it in the kitchen, for a reason.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I thought that was because of the peculiarity of bacteria in the wooden dams that hold the water supply for the area around Sydney, NSW.
Certainly not a worldwide norm.
--
---
Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8,-122.5
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@XReXXGFXXv.usenet.us.com wrote

No such animal.

Precisely the same type of dams are used around Sydney as are use virtually everywhere else in the first world.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I am remembering my visit incorrectly, then. My host, in Mossman, pointed out the risk of the DWH temperature, and commented on the wood that was a part of his water supply, reaching up and picking a sliver out of the nozzle in the shower.
What explanation is there for this heat requirement, which doesn't exist in most other parts of the first world?
--
---
Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8,-122.5
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@XReXXGFXXv.usenet.us.com wrote

He was clearly pulling your leg.

Basically storage hot water services can end up with a significant problem if they arent run at a high enough temperature to kill bacteria, in situations where the water supply isnt chlorinated like with wells etc.

It does actually. Most obviously with Legionaire's Disease.
And the use of unchlorinated wells with residential property is much more common in north america too.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I have lived on well water for many years. Some people treat water drawn from shallow wells, but I don't know of anyone that does any treatment to deep wells.
I find recommendations to raise the temperature to 170f to kill hydrogen sulfide to get rid of a rotten egg smell, but even those sites say it is harmless.
Most of the advice is to set the temperature to 140 if you have a dishwasher, 120 otherwise.
--
---
Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8,-122.5
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@XReXXGFXXv.usenet.us.com wrote

Few chlorinate it properly like you see with town water supplys tho.

It is in those small quantitys.

Those that know anything about Legionella dont. http://www.ihf.ie/news/innsight/98-12inn/page1-4.htm#anchor23477
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Let's go back to Australia: http://www.safetyline.wa.gov.au/pagebin/codewswa0210.htm "Long exposure at 50C or shorter exposure at higher temperatures is sufficient to kill the bacteria." That would be 122F.
I remember The American Legion meeting, but that was warm water in a cooling tower, not a domestic water heater.
"Proliferation of L. pneumophila is promoted by: a wet warm environment (range 25-42C); optimum temperature (35-37C); stagnation or low water turnover; high microbial concentration including algae, amoebae, slime and other bacteria; presence of biofilm, scale, sediment, sludge, corrosion products or organic matter; presence of certain materials such as natural rubber fittings which may be a nutrient source. "
I don't think that describes my domestic water supply. The recommendation for 120F still stands. That won't scald, and it will kill Legionella bacteria.
--
---
Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8,-122.5
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@XReXXGFXXv.usenet.us.com wrote

No thanks, that specification of the minimum temperature that storage hot water heaters should be set to is just about universal right thruout the first world now.
Because Legionella is a real problem with showers.

Thats on the low side of the recommendations, 60C, 140F is much more common. http://www.google.com.au/search?q=Legionella+60+C

Sure, and after that it was realised that storage hot water services could be a real problem with Legionella when they are set a lower temperatures to avoid scalds with kids and the elderly etc.
Presumably we didnt see that much of problem with Legionella in storage hot water systems because most didnt deliberately turn back the setpoint much before that American Legion meeting made it clear what a problem that particular bacteria could be.

Thats just cooling towers, different animal entirely to storage hot water services.

See above.

No it doesnt if you actually have a clue about Legionella

Have fun explaining the common code requirement of 60C, 140F
http://www.dhmh.state.md.us/html/legionella.htm says you are just plain wrong using rigorous science.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I've learned that further discussions with you would be pointless.
Nick
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

No, I don't think this is the way to go. When using warm water to heat cool water, the smaller the temperature difference along each section, the better as far as entropy goes.
That is one of the reasons why counter-flow hx are so good. The warm water is never more than a few degrees above the 'cool' water. Where the 'warm' water is the hottest, the 'cool' water has already been heated up to almost the same temperature. And where the 'cool' water is the coldest, the 'warm' water has already been cooled to almost the same temperature.
Compared to a parallel flow, where the 'warm' and 'cool' water start out with vastly different temperatures and aproach each other over the length of piping.
With your 'infinite' tank idea, you end up with very cold greywater, but the freshwater is hardly warmed at all. Making the two tanks nearly equal, you approach the limits for a parallel flow system (e.g. grey and fresh leave at the same temperature, about (100+55)/2 = 77.5F.
I take it you've considered what the pressure drop would be with the flow rates? Check the greywater side pressure drop carefully. Although you have larger x-section, the *available* driving pressure for a shower drain is just a few feet of water.
daestrom
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Suppose we take a shower and collect 100 F greywater in the upper part of a $30 100'x4" black plastic corrugated drainpipe coil containing 3 $20 100'x1" pieces of black plastic polyethylene pipe, with bidirectional plug flow, like this, viewed in a fixed font like Courier:
shower in | --------->--------------------------------> hot water to shower | | Tl | --------- sewer --------- | | Tg | out | 120F | | | | | | | | | ^ | | | | | | | | | |1" |4" | | tank | | | | | | water | | | | | | heater | | | | | | | | | | | | | | | | | | | | | |---- | | | | | | 55F | --------- P --------- | ---- Tc | -----------------| <- |-------------------< cold water supply ----
Now we disable the water heater and run a slow, low-power pump P (eg Grainger's $120 4PC86 (Taco 003-BC4-2) 1/40 HP 120V 0.43A pump) if Tg - Tl < 5 F and Tg - Tc > 5 F, and enable the water heater again when Tg - Tc < 5 F...
Is this a GFX-Star? It's hard to tell from the website description.
20 UPIPEx.5'U-value of 10' section of 3 1" pipes (Btu/h-F) 30 CFRESH=1.25*8.33'thermal capacitance of 10' of fresh water (Btu/F) 40 VGREY*3.14159*(2/12)^2'volume of 10' of greywater (ft^3) 50 CGREY=VGREY*62.33-CFRESH'thermal capacitance of 10' of greywater (Btu/F) 60 CSERIESRESH*CGREY/(CFRESH+CGREY)'caps in series (Btu/F) 70 RC=CSERIES/UPIPE'combined time constant (hours) 80 EXPF=EXP(-1/60/RC)'exponential factor 90 FOR SHOWER = 1 TO 100'simulate showers 100 FOR M=0 TO 89'simulate 10 min shower every 90 minutes 110 IF M>9 GOTO 220'rest vs shower 120 IF SHOWER <100 GOTO 150 140 PRINT 400+M;"'";M,TG(9) 150 TGT=TG(0)'save original Tg(0) for later Tg(1) calc 160 TG(0)=(100*CFRESH+TG(0)*(CGREY-CFRESH))/CGREY'move greywater in 170 FOR S=1 TO 9'pipe section (9<->fresh water in and greywater out) 180 TGP=TG(S)'buffer 190 TG(S)=(TGT*CFRESH+TG(S)*(CGREY-CFRESH))/CGREY'move greywater down 200 TGT=TGP'buffer 210 NEXT S 220 IF (TG(0)-TF(0))>5 OR TG(0)<60 GOTO 290'no pumping 230 PUMP=PUMP+1'pump in fresh water at bottom 240 IF SHOWER>49 THEN HEAT=HEAT+CFRESH*(TF(0)-55)'gain from gw 250 FOR S=0 TO 8'shift fresh water up 260 TF(S)=TF(S+1) 270 NEXT S 280 TF(9)U'move cold water in at the bottom 290 FOR S=0 TO 9'rest 300 TFINAL=(TF(S)*CFRESH+TG(S)*CGREY)/(CFRESH+CGREY) 310 TF(S)=TFINAL+(TF(S)-TFINAL)*EXPF'new fresh temp (F) 320 TG(S)=TFINAL+(TG(S)-TFINAL)*EXPF'new grey temp (F) 330 NEXT S 340 NEXT M 350 NEXT SHOWER 360 SHOWERGYP*10*CFRESH*(100-55)'50 showers with no GWHX (Btu) 370 PRINT HEAT,SHOWERGY,HEAT/SHOWERGY,PUMP
time gwout (min) (F)
0 55.50439 1 55.66506 2 55.83802 3 56.02375 4 56.22276 5 56.43565 6 56.66306 7 56.90572 8 57.16441 9 57.43995
231607 234281.3 .9885854 1458
Looks good on paper, with 98.9% heat recovery :-)
Nick
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@ece.villanova.edu wrote:

This is so very very close to a GFX Star it isn't funny
What the Dr argues for is a el-cheapo electric water heater that is used solely as a storage tank. The inlet to the pump is thru a check valve that ties to the drain connection of the water heater/storage tank. Hot out of the heat exchanger then goes to TWO places.
1. To a tempering valve to limit scald risk. the other input of the tempering valve is the output of the normal hot water supply (electric, NG, LP, or same inputs tank less)
2. Cold in on the water heater/storage tank.
Hot Out of the water heater/storage tank goes to Cold in on the normal water heater.
Nick's figures and the Power-Pipe folks argue that the heat recovery is equivalent to a 12-18KW electric heating element (for a 60 inch GFX). In testing of the the GFX done at at least a couple of universities, they found that the upper heating element in an electric water heater NEVER TURNED ON in ANY of their testing.
The heat recovery of a GFX when used in this configuration jump 15-20 percentage points and becomes an almost level 65-75% Course we will have 2KW/day losses in that storage tank. But with a CONSTANT input ot the normal Hot water heater of 85-90 F, it will merely LOAF along to deliver the HOT water needed.
One of the reasons for the higher heat recovery is that the flow rate thru the coil LEAPS. The Taco pumps will move up to 20Gal/hr depending on model to 20 feet. More realistically a Taco 006 or Taco 008 will delvier upwards of 10Gal/hr at 10 feet of height. Now we have 2x-4x MORE flow thru the coil than is flowing in the greywater. The graphs on the GFX web site illustrate what happens with higher coild flow rates.
GFX Star controls the pump via one of two methods
a. Timer - showers at KNOWN times EVERY day
b. Differential temperature controller -sensors on coil and inlet to the heat exchanger (GFX or Nick's) will trigger the pump when temp difference exceeds a set point - i.e. 2 or 3 degrees
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I'm still not clear on that, after talking with Carmine again. One diff might be beneficial stratification in the greywater drainpipe, vs full mixing in a conventional greywater tank. At any rate, with 98.9% heat recovery, we might heat 50K Btu/day of water with 550 Btu/day, eg a 7 watt night light burning 24 hours per day :-)

Dr. V got US Customs to sieze Power Pipes at the border, based on a theft-of-trade-secrets charge, but they seem to have gotten around that.

We also discussed some testing techniques that were biased against GFX.

Maybe a lot more, with greywater plug flow.

That isn't part of my scheme, but another circulating pump could increase the velocity through the coil and the conductance inside the coil...

That's quite different. No timing for me, and I'd turn on the pump when the gw-fw temp diff at the output is LESS than 5 degrees.
Nick
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Power-Pipe now has a US web site that gets them around the customs issue.
The pump with differential temperature control is the secret to higher recovery rates. Flow rate thru the coil in excess of flow rate of greywater will more efficiently transfer heat to the potable water.
Actually you could take this a step further and use a water storage tank intended for solar applications. It has an internal heat exchanger, and you could route a working fluid thru Nick's, a GFX, or a Power-Pipe that was NOT water for higher heat capacity.
snipped-for-privacy@ece.villanova.edu wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.