Not High Tech, but Technology in the Classic Sense

A friend recently wrote us asking about running out of hot water during showers, and it reminded me of a simple fix. She wrote:

"Hello friends and family. Can you please help me out? We are having trouble getting enough hot water for showers at our house. We just bought a new hot water heater, 50 gallons, and we still can only take two SHORT showers one after the other if we want hot water to last.

I have been doing a lot of research and calculations. Can you tell me about your own household? I'm wondering if my expectations are too high.

1) How many gallons is your heater?
2) Gas or electric?
3) Brand?
4) FHR #? (First hour recovery number is located on your tank) This number is important.
5) How long are your showers?
6) How many showers can your family comfortably take in a row?

Do you run out of hot water? I am going nuts!!!! I think we need an 80 gallon tank!!"

Generally speaking, gas and oil heaters can heat water faster than an electric heater, but this is just a common product engineering trade-off, not a law of physics. I replied that a 50 gallon gas or oil heater is a bit small for a family of four, and that it is definitely too small if it is electric.

Either the shower needs enough BTU/Hour (British thermal unit is the amount needed to raise 1 pound of water 1 degree Farenheit) to keep up, or it needs a large thermal reserve in the tank to compensate for the gap between production and usage. The legal limit for a shower in the United States is 2.5 gpm (gallons per minute), although you might have a higher flow rate if you are using an older showerhead or someone removed your flow restrictors for a high pressure shower (this article describes how it is done, so it should help you check to see if the restrictors are in place in your shower).

If your shower is running at 2.5 gpm and your water source is 40 - 50 degrees (meaning 60 degrees increase is required to boost the temperature to over 100 degrees), you need a heater with a minimum 75,000 BTU/hour to keep up with demand, according to this handy calculator. If you are using a shower that produces 4 gpm, you will need 120,000 BTU/hour to keep up. So if your pressure is more than you need, one solution to hot water capacity is to reduce the water usage using a reduced flow shower head.

Most people are looking for more pressure, not less, so this probably isn't a practical solution. Another option is to add a tankless hot water heater to one of the showers. You can also add a storage tank (e.g., SuperStor) to an existing hot water heater for less than buying a new higher capacity hot water heater. However, before upgrading the hot water system, there is a simple solution for getting the most out of the heater that many people overlook: turn up the temperature on the heater.

We have a 80 gallon gas fired heater. We can take an unlimited number of showers without running out of hot water. However, when we first moved into the house, we had the same problem. The water temperature on the heater was set to the minimum. After I turned up the heat to the maximum we problem went away completely. This is for two reasons that are mutally reinforcing:

1) If the temperature is set higher you will need less hot water to mix in with the cold (e.g., 170 degrees hot + 40 degrees cold mixed 50%/50% = 105 degrees, whereas 120 degrees hot + 40 degrees cold must be 80% hot water to get 104 degrees).

2) If the tank can't keep up with your usage, it has a bigger head start if the temperature is set higher. As the cold water refills the hot water tank, the tank temperature falls, and when it is below the 100 degrees, the shower will no longer feel hot, even with the cold turned off. So if your temperature is set to 120, when 20% is depleted, the tank water drops to 104 degrees. If the temperature is set to 170 degrees, the temperature will not cross the 100 degrees threshold until more than half the water is depleted. This is an oversimplification because even as the heater is falling behind, the heater slows the rate of temperature decrease - this static temperature mix calculation does not reflect the heating done during the decline. However, it is also follows that the tank will have more time to raise the temperature when it has until 50% depletion instead of 20% depletion.

There are several drawbacks to increasing the temperature of the heater, but they are not dealbreakers to me:

1) Heat loss from the tank to the surrounding room is greater, but modern tanks are very well insulated so this is less of an issue than older tanks. Also, my hot water heater is in my basement, so the heat loss warms the unheated basement a little.

2) You can scald yourself on the tap water, but everyone gets used to it so really you just have to warn guests. If you are concerned, you can try turning up the water in increments to give everyone time to get used to it.

3) If you have hard water, the minerals come out of solution more, so you might need a water softener. If you have hard water, you should get a softener anyway, because your pipes, valves, and showerheads will fill with minerals over time which is very difficult to fix.

So while not high tech, it is technology (definition: applied science) that we appreciate every morning.

One Laptop per Child

I gave each of my children their own laptop. It started with old laptops that my wife and I outgrew (a Toshiba Tecra 8100 and a Dell D600), but these same models are available inexpensively on eBay. The 8100 usually goes for about $100, depending upon the specs. The D600 usually can be found for $250 if you are patient.

We have standardized on these two models for the same reasons companies standardize - it makes it easier to service and support them. This way I can stock extra power supplies and other spare parts, and if two were to fail I can probably combine them into one working machine. You can also learn the quirks of the machines so you know what it will take to restore an imperfect unit. For example, the Tecra's often are listed with 128MB of RAM, because they frequently have one of the DIMM slots fail if the unit overheats from blocking the cooling vents for an extended period of time. 128MB of RAM is just not enough for most things, but you can buy a single 256MB DIMM for $40, and then the unit is perfectly usable again. Also the backlight inverter often works itself loose or fails, and this is a 3 minute repair using a $10 - $20 part, and you used to be able to get it done for free by Toshiba due to a recall.


We use a Windows 2003 Server for domain controller, Microsoft Exchange server, and file server. Everyone gets their own user account, but I have the system log them in to their laptops automatically. This really helped when they were younger and couldn't be relied on to navigate the "Ctrl-Alt-Del" windows login and remember passwords. To do this, you use the registry editor to change settings in the following group:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon

1. Set "AutoAdminLogon" to 1
2. Set "DefaultUserName" to the user name
3. Set "DefaultDomainName" to the windows login domain name
4. Set "DefaultPassword" to the user password

I use Windows XP on all the laptops, which works fine with 256MB of RAM. These settings also work for Windows 2000.

The first software I put on the laptops was FasttMath by Tom Snyder Productions. This program is basically math fact flash cards for the PC. It is well worth it because it keeps track of their progress, provides fact memorization games to keep them interested, and provides status reports for you to monitor their progress. It is mostly used in schools, but they will sell single copies to consumers directly. I highly recommend it.

The next software I installed was SafeEyes a content filtering program that runs on the laptop. I have mixed feeling about this software because it does effectively block content, but the number of times I had to manually reconnect the software was an excessive drain on sysdadmin support hours. It may be because all of the computers I put the software on also used wireless connections, which maybe confuses SafeEyes as the connections come and go. If you are using wired connections or if you're not worried about manually reconnecting it from time to time, you should check out the 30 day free trial.

Aside from content filters, you can create a whitelist of sites on a computer by disabling DNS and putting only the sites you want to allow in the local hosts lookup file. On Windows XP, this can be found in C:\WINDOWS\system32\drivers\etc\hosts. You could put entries in the hosts file like this:

165.193.130.178 http://www.funbrain.com/ funbrain
199.181.132.250 http://www.disney.com/ disney
209.9.8.79 http://www.webkinz.com/ webkinz
77.73.32.120 http://www.miniclip.com/ miniclip
208.139.194.177 http://www.starfall.com/ starfall

The problem with creating a whitelist is that the IP addresses can change, or there can be more than one ip address that is used for load balancing and failover of the site. But this is a low tech solution that can protect the innocent, but kids who are older and motivated to find a way around it can easily do so.

Aside from web browsing and FasttMath, the most common things they use the laptops for are drawing in Paintshop Pro, writing homework in Micrososoft Word, browsing family photos, watching movies (family or commercial), and loading up their iPods with my mp3 collection. My sons also have the Timex Ironman Datalink watch which can synchronize appointments, contacts, and notes with Microsoft Outlook. All of them are strangely obsessed with Google maps from time to time, but then again, isn't everybody?

Scamming the Scammers - an eBay Rant

I have to admit that sometimes I get taken on eBay. The great thing about eBay is that if you are a smart buyer it all works out in the end for you anyway. I have probably spent about $25,000 on eBay over the years, and never lost money. In previous posts I discussed the VOIP equipment, the home theater PC, and Tivo upgrade gear that I bought on eBay.

On three occasions I did have to take the time to file disputes and follow through on the resolution process. When I buy on eBay I have learned to take the time to detect obvious red flags and move on. In particular, I avoid:

• Sellers who don't take Paypal
  
• Sellers outside the US (possibly Australia, Canada or UK for unique items)
  
• Feedback scores lower than 100
  
• Feedback positive % lower than 98%
  
• Feedback that doesn't pass the smell test: all recent, all feedback on very low dollar items, lots of feedback from the same person, lots of feedback that sounds like it was written by the same person, etc.

But that isn't always enough. Once I bought an Emeco bar stool on eBay and received a very cheap knockoff. After the due diligence with paypal I received my refund, and Emeco gave me a great discount on the real thing when I told them my story. By alerting them to someone who was pirating the Emeco brand, I did them a service and they happily returned the favor.

Always pay by Paypal. If a seller doesn't take Paypal, it is because they don't want to be bound by Paypal buyer protection rules, which is either cluelessness, a sign of bad history with chargebacks, or a potential scam. All of these reasons signal a seller that you should avoid. Please don't ever wire money, send a check, or give your credit card details to anyone on eBay. Also do not ever send someone money after they send it back to you. This is a confidence trick - they send money back to get you to trust them so that you send a paypal direct transfer (which doesn't carry buyer protection), or another payment mechanism you wouldn't ordinarily use.

Be mindful of the 30 day deadline for disputing a transaction in Paypal. Some sellers will try to trick you into waiting past the 30 day window, so file a dispute as soon as day 29 arrives if you don't have your item yet, no matter how nice the seller sounds. You can always close the dispute later if the seller delivers, without much time or trouble to either you or the seller. Don't feel guilty; the seller doesn't deserve your money yet if you still don't have the product 30 days after paying for it. If the seller complains, tell them you will close the dispute and leave positive feedback as soon as you receive your item.

Take notice of the Paypal protection threshold, it can be either $200 or $2000, depending upon the seller. The eBay listing will show the level of protection under the payment section. The $2000 threshold is only offered for sellers with established positive feedback and verified Paypal seller accounts.

I would also encourage you to fund paypal using your credit card instead of a checking account debit if you are unsure you will be able to file a dispute within the required 30 days or if the amount of the transaction exceeds the Paypal protection threshold. If Paypal won't give you your money back, you can take it up with your credit card company and get the charges reversed.

Always ask questions if a listing is ambiguous, even if you think it is obvious, because it may be left unsaid to mislead you. For example, accessories you "know" come with something probably will not be supplied if the listing doesn't mention them. When a seller wants you to know the item is complete as shipped from the manufacturer, they usually say "factory sealed" or "NIB" (meaning new in box). When a seller says they are unable to test something, it probably means it doesn't work but they're hoping you will take a chance on it.

Always ask your questions on eBay using the "ask the seller a question" link so that you have proof of their answers, since direct email doesn't leave an audit trail that eBay or Paypal can rely on. Even if you are buying something "as is", the statements they make in the listing or in response to your questions must be true, thereby limiting the scope of the "as is" disclaimer. If the seller doesn't answer your question, this is a bad sign and you should not bid at all.

Just this week I was defrauded by a seller offering Adobe Creative Suite 3 Master Collection. The seller said they hadn't registered the software in response to my question, they accepted Paypal, and had positive feedback. It was a great deal, and I bought it.

After I paid, I noticed they had a different name on their emails than the name on the Paypal statement. This raised my suspicions, but could be innocent. Next, I saw the originating city on the Federal Express tracking screen was different than their eBay user information. While this could also be explainable, it raised my suspicions still further. After that my suspicions were confirmed when the seller wrote to me and said "I am having trouble with my Paypal account (I really wish there were an alternative to it!) So I am going to issue you a refund. Once I do, could you resend payment to name.changed@mailnull.com?" The mailnull is a nice touch, because it is a mail forwarding service, being used by the seller to try to cover their tracks.

Now that I knew the seller was a fraud, I decided to get the refund by playing along. This way neither Paypal nor I would have any inconvenience in recovering the money. "Sure, I don't see why not" I replied. Later I wrote back to say I hadn't sent the money yet because I didn't see the refund process on Paypal yet. In the meantime, the package arrived and the CDs were clearly bootleg. I called Adobe with the serial number, and they confirmed it was an invalid serial number.

The seller refunded the money on Paypal and sent a Paypal payment request. As soon as I confirmed the refund, I alerted eBay, Paypal, and Adobe. I never even tried to install the software; I just sent the disks to Adobe as evidence in the case their anti-piracy department is pursuing against the seller.