How to Identify Your Hydronic System

Ciculator pumps.

There are good reasons to understand the basics of your hydronic heating system, even if it’s just knowing how to identify what type of system you have. It helps the service technician when you can tell him what type of service call he’s responding to and he can troubleshoot more effectively. It also helps you weed out the inexperienced service technician or contractor. I’ve even seen home inspection reports that went into great detail about a home’s hot water heating system that turned out to be steam. True!

Starting with the question, Is this steam or hot water?, let’s go down to the boiler room.

A hot water heating system usually works by pumping heated water through a system of pipes, to the radiators, and back to the boiler. A dead giveaway to the hot water system is the pump. There are a few old hot water systems out there that don’t use pumps, but by-and-large, most have a pump. And frankly, if you have a hot water system that’s old enough to be “gravity” operated (without a pump), you should be thinking more about identifying its replacement.

Steam boiler with gauge glass.

A steam system would rarely have a circulating pump. There are some steam systems that use the hot water below the boiler’s water line as a heat source for a domestic hot water circuit or small heating loop, but they’re fairly uncommon.

A steam boiler should always have a gauge glass on the side of the boiler. This allows you to see the water level in the boiler. A hot water boiler doesn’t need this because the whole system is (or should be) full of water.

Now let’s say you’ve straightened out your home inspector on the fact he’s actually looking at a steam boiler. But now he’s too intimidated to ask if it’s a one-pipe or two-pipe system. You’ll want to volunteer this information. We need to get out of the boiler room and head upstairs for this.

You can usually tell a one-pipe from a two-pipe steam system simply by looking at the radiator. One-pipe will have just one pipe connected to the radiator and two-pipe will have two. It’s that simple. But it’s an important distinction. The two systems operate very differently and require a different mindset for troubleshooting.

One-pipe steam radiator.

Another distinction between the one-pipe and two-pipe steam system is that the one-pipe should have an air vent on the side opposite the steam inlet. But you need to be careful with this one — I’ve seen some underperforming two-pipe systems “fixed” by adding a vent to the radiator. It’s a bad idea, but they’re out there.

Most (not all) two-pipe systems will also have a steam trap on the radiator outlet. This is the device that can fail and cause the inexperienced service technician to put an air vent on a two-pipe radiator!

Two-pipe steam radiator.

So there you have it. Now when you call for service, you can tell your service technician exactly what type of system you have and help them better diagnose your service problem. (Or impress your home inspector.)

Heidronically yours,

Wayne

Less is More

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Turn it down. Turn it way down.

I’m referring to the pressure setting on your steam system. The single easiest thing you can do to improve the performance, comfort and fuel economy of your steam heating system is to reduce the pressure. It should also be the first thing you do when things aren’t working right.

It’s tough to do. It seems counterintuitive. That back addition or attic bedroom isn’t getting enough heat, so it seems to make sense to turn up the pressure to force the steam into the far reaches of your system. But it seldom works. And what’s worse, it usually creates even more problems.

Most of the components in your steam system operate best within a range of pressures. Take main air vents, for instance. They come in lots of shapes and sizes AND pressure ranges. I was recently in a home with end-of-main vents that weren’t working properly. They seemed to vent OK at the beginning of the cycle, but appeared to stop working before the main was completely vented.

As it turns out, these particular main vents are designed to operate at less than 3 PSI. At higher pressures they close off tightly ­— rendering them essentially useless. A check of the pressure control had the system set at 7 PSI. So as the steam pressure rose inside the pipes, the vents worked until the pressure got to 3 PSI, then they’d stop venting. Since this was a one-pipe system, the radiator vents had to do double duty venting the rest of the main, all of the risers and the radiators.

A standard Honeywell Pressuretrol

This meant the radiators farthest from the boiler were not getting much heat. By the time the radiator vent in the attic allowed steam in, the radiator in the dining room (where the thermostat is located) had been full of steam and heating for some time.  It satisfied the thermostat and shut the boiler off just as the attic radiator was getting started.

When I turned the pressure down at the boiler, the main vents were able to completely vent the mains and allow the radiator vents to get back to work, venting only the risers and radiators. That’s when the attic radiator finally got some steam and heated the previously unusable attic space.

 

It can be worse on a two-pipe vapor system, as this usually has just one vent at the end of the dry return. If this single vent shuts off on pressure, everything stops heating. But the boiler keeps firing, trying to raise the pressure — wasting fuel.

A Honeywell Vaporstat

So what pressure is right for you? I haven’t met a residential space heating system yet that needed more than 2 PSI. And many need even less. In fact, on most of the replacement boilers I install, I routinely discard the factory pressure control that comes with the boiler and replace it with a Vaporstat. The factory-supplied device can only control the pressure down to 1PSI.  A Vaporstat regulates the pressure in OUNCES, which allows me to control the system at LESS than one pound of pressure — usually between 4 and 10 ounces. This can save a significant amount of fuel while improving comfort AND system performance.

Heidronically yours,

Wayne

The Abominable Steam Boiler

One of my favorite holiday TV specials is Rudolf The Red-Nosed Reindeer. I love the part where Hermey tames the Abominable Snowman by fixing his toothache. It got me thinking about steam heating systems. (Yes, that’s the weird way my mind works.) Like the Abominable they’re often misunderstood and lonely.

Your steam heating system can seem mysterious and sometimes even a little scary or creepy. This large hunk of metal sits in the dark recesses of your basement making odd hissing, panting or clanging sounds. Every so often it rumbles to life and sends heat upstairs to the rest of the house, but mostly it’s the reason you don’t like going down “there.”

It doesn’t mean to be so scary. It’s just lonely and needs a little love and understanding ­— like the Abominable. Once you get to know him, you’ll realize he’s a softy at heart and he just wants to be helpful and accepted.

If we’re going to get to know this monster, we should probably start at the heart of the system. The boiler is where the heating cycle begins and ends. In its simplest form, it’s a hollow block of cast iron with a burner underneath. It’s partially filled with water that the burner heats up to a boil (hence, why it’s a “boiler” and not a “furnace.”). When the water starts to boil it creates steam. The steam exits the top of the boiler through pipes that distribute the steam to all of the radiators in your house.

The radiators give up the heat of the steam to your rooms, which cools the steam to the point that it condenses back to water in the radiator. The water now drains back through pipes to the boiler and gets heated back to steam in a cycle that continues until your house is warm enough and the boiler shuts down until your thermostat calls for heat again.

The combustion byproducts are safely vented through the chimney and out the roof. It’s a simple and elegant process that repeats itself over and over for many years —making you warm and comfy and not asking for much in return.

When things are working right it’s quiet and efficient. When they’re not, it can be loud, uncomfortable, inefficient and just plain grumpy. Like the Abominable, sometimes it needs some attention to keep it content.

We’ll talk more in future posts about some different types of steam systems and some simple things you can do to keep your Bumble humble.

Happy New Year!

Heidronically yours,

Wayne