In the last article, “Is your boiler stealing your money?“, I discussed why most boilers are ripping you off. Contrary to what almost every HVAC saleperson or tech will tell you, your boiler does not operate at 84% efficiency. It doesn’t operate at 80%! Heck, much of the year, it doesn’t operate at 50% efficiency!
To review, the reasons for this include:
- High operating temperature
- Minimal insulation
- Infrequent use
- → Outrageously high standby losses
In this article, I’m going to discuss how to do it right. But if you’re too lazy to read the entire article, stop right here and go to the Energy Kinetics website.
But first, I’m going to save you $10,000….
What not to do next
Do not do what I did before I knew better. After learning how terribly inefficient my existing boiler was, I talked to lots of sales people, read the literature, and studied all I could about system efficiency. Unfortunately, I got fed a lot of inaccurate information and spent $10,000 on a super high efficiency boiler – the highest efficiency rated boiler on the market. It was supposed to be the most efficient system available with super-low standby losses. Well, they lie, or they’re ignorant. Or they lie and they’re ignorant.
No, the boiler is in fact super-efficient – if it runs constantly. The boiler is indeed 92%-95% combustion efficiency and the indirect heated water tank is very low loss. But the boiler never runs at full capacity unless it’s really cold out. That’s how they’re supposed to run. So it cycles on and off because it has to stay hot all the time just in case. And the warmer it is outside, the more time it spends cycling and the less time it spends heating my water.
So I still turn it off during the non-heating months because it’s wasting so much oil just staying hot. Back to the drawing board!
The HVAC ‘pros’ out there might think that I’ve got it plumbed wrong or have some other problem. Nope. I’ve checked everything. This is pure, old fashioned standby losses (or more accurately called idle losses). If you read the references in my previous article, you’ll know that I’m right. During the non or minimally-heating months when the boiler spends more time idling than it does working, the efficiency plumets to well below 50%. Frankly, it sucks and it’s wasting hundreds of dollars a year doing absolutely nothing.
If I was in power, long ago I would have outlawed this type of boiler, which now comprises almost the entire installed base of boilers, because they waste so much energy. Seriously, millions of gallons a year of fuel oil, propane and natural gas get wasted because of this incredibly stupid and wasteful system design.
Some solutions to the problem
The simplest path
The ‘simplest’ solution is to install a dedicated water heater plumbed in series with your boiler and turn the boiler off during the non-heating season. This may sound drastic, but it can pay off in just a few years.
The advantage of this method is that it’s so simple to do that any competent plumber should be able to do it without screwing it up. It’s an afternoon job. They just set it up so that the water keeps flowing through the boiler during the off season, then goes into the new water heater and then to your home’s hot water lines.
Read that again. The water runs through the boiler then into the new water heater. The dumb-*ss who tried to do this in my home (before I bought it), plumbed it the other way – into the auxiliary water heater first then through the boiler. Why is this wrong? Think about it. You’re heating the water in the auxiliary water heater. The water then goes into the cold boiler, which sucks the heat out of the water trying to heat up a big hunk of iron. So you end up with luke-warm water. Folks – this isn’t rocket science, you just have to think about it a little bit…
The simplest path ain’t so simple
Things are never quite so simple. While this solution works great and eliminates all the waste from summertime use of your system, depending upon the cost of your utilities, it might not actually save you much money. Or, it might save you a ton of money.
I’ll use my area as an example since I know all the fuel costs. Around here, right now (Spring of 2011), oil costs around $3.55/gallon and electricity is about $0.16/kWh. Propane is about $3/gallon and natural gas is $1.55/CCF. What’s this mean?
Let’s compare what it might cost to heat hot water for six months of the non-heating season using a variety of different fuels and heaters. The assumption here is a family of four using 120 gallons of hot water per day.
Conventional boilers (this is what we’re comparing others against)
- Oil: $730
- Propane: $930
- Natural gas: $440
Storage tank heaters (you’re typical cylindrical tank type heaters)
- Electric: $665
- Oil: $597
- Natural gas: $360
- Propane: $758
Other technologies, with storage tank
- Heat-pump water heater: $299
- Geothermal heat pump: $199
- Cold-start/finish oil boiler: $391
The first thing you notice is that natural gas is really cheap compared to oil or propane. In fact, currently, there’s an economic imbalance because we get gas domestically and there’s been a ton of reserves discovered whereas with oil, well, you don’t have to be reminded about oil…
But propane is complicated. If you own your own tanks, propane costs fluctuate wildly throughout the year. It might be $3/gallon in winter and half that in the summer! So, in theory, if you had big tanks, you could buy it cheaply during the summer and cut your energy bills in half. This is a story for another article….so let’s get back to the point.
The point is, you can’t just rush out and buy the cheapest tank water heater and expect to save hundreds on your summer water heating bill. If you augment that inefficient boiler by installing a conventional electric water heater, you’ll only save $65/year if you live around here where electricity costs $0.16 per kiloWatt-hour. On the other hand, if you live somewhere with electricity at $0.10 per kWh, you’ll save over $300 per year! You’ll have to figure out the numbers for your own actual utility costs.
On the other hand, if you have natural gas available and you’re currently heating with oil, even at the expensive cost we have here, you’ll save $370/year by installing a relatively cheap gas tank water heater. But, if you have a gas boiler and you install a gas tank water heater, you’ll only save $80/year. It’s enough to boggle the mind!
The right solutions
Take a look at the “other technologies” section. This is where geothermal heat pumps and heat pump water heaters really shine. They extract a lot more heat out of every Watt put in than does a normal electric water heater. So a heat pump water heater will save you $430/year and a geothermal based water heater will save $530/year. Those are some serious savings.
The last device listed is a “cold start/finish boiler.” This looks just like a normal boiler and is a drop-in replacement for your existing boiler, but it actually works intelligently. Rather than sitting around hot all day long, after it’s done heating your water, it turns off. The best example of this is the Energy Kinetics System 2000 (pictured at the start of this article).
I’m going to sound like a salesman, but try to ignore that. I’m not. I get nothing from Energy Kinetics. I did tour their factory because it’s close to my house, and I think I got a few brochures, but that’s it. So much for my disclaimer…
Anyway, the EK2000, as it’s called, does something that all boilers should but almost none do. Say it’s heating water during the summer. The electronics in the boiler detect when the boiler is done heating up the water tank. Then, it turns off the burner but keeps the circulator pump going that’s heating up the water tank until as much of the boiler’s heat has been transferred to the tank as possible. This still isn’t perfect because the water tank is kept at 120-130 degrees, so there’s still some losses. But it’s much less than a conventional boiler. Plus, the EK2000 won’t keep on cycling on and off when there’s no need to. Using this simple technique, it obtains a real efficiency that’s vastly higher than conventional boilers in months that don’t require much or any space heating.
So if you’re looking to replace your existing boiler, it will behoove you to check out the EK2000. However I’ll warn you, the competitors will badmouth it because “its not like the ones they’re used to.” They’ll hand you a lot of misinformation (it’s called FUD – fear, uncertainty and doubt) to scare you out of buying it. Then they’ll sell you their shiny cast iron boiler using technology from the 19th century that they make a big profit margin on.
But here’s the truth. I’ve talked with techs and users of the EK2000 from around the country and they swear by it. It actually works and it doesn’t suffer from the problems that the competition complains about.
From a practical standpoint, you have to look at your specific situation. If you’re building a new house, you might choose to go all geothermal for heating and hot water, whereas in many cases, this wouldn’t be practical as a retrofit. In some cases, it will make sense to use a dedicated heat pump water heater while in others, you might not want to do anything. It’s complicated…
Hopefully this has clarified more than it’s confused. There really are a lot of parameters that you have to consider. But if you get nothing else out of these articles, I hope you understand that the common and familiar way of doing things with boilers is horrendously inefficient and every year you do things the same old way, it’s probably costing you hundreds of dollars in wasted energy.