Expanding on a common boiler question
Expansion tanks must be installed on the supply side of the boiler—where cooler water enters the boiler to be heated again.
Expansion tanks must be installed between the boiler and the circulator, and they must be 18 inches or more away from the boiler’s vent connector.
Most expansion tanks work properly when standing upright, but some models allow for a horizontal installation.
Signs of a poorly installed expansion tank include rapid pressure increases, strange new noises, and malfunctioning bleed valves.
Wondering where the expansion tank should be installed on your boiler? The expansion tank, or thermal expansion tank, is a 3 to 5 pound tank that sits close to boilers and water heaters, performing a small but necessary function. Inside is a trapped pocket of air that expands and contracts in response to pressure. When water is heated, it expands, so the tank allows water to expand and pushes back as the water cools, keeping the pressure at safe levels while heating the water to high temperatures.
To do that job properly, the expansion valve needs to be installed in the right spot on the boiler. Let’s dive into the details of where to install an expansion tank and when to hire a boiler professional for help.
The most common spot to install the expansion tank on a boiler is slightly above or close beside the boiler—wherever it’s easiest to strap the tank in next to the supply pipe and secure it for the long term. Here are the rules that the tank placement should follow:
The tank should be installed at least 18 inches from the vent connector of the boiler.
The tank must be installed on the supply side of the boiler, not the “cool” side of the boiler where returning water comes. Supply pipes are usually higher and marked with the direction of water flow.
The tank should usually be installed upright.
The tank must be properly supported with metal straps or brackets. It cannot be attached to the piping and left to hang.
The tank must be installed between the shut-off valve and the tank inlet.
The tank must be installed above the pressure relief valve on the boiler.
If the boiler has a system circulator on the supply side, the expansion tank must be installed between the boiler and the circulator.
Boiler manuals have more specific instructions for installation. Keep in mind that larger boilers may need larger expansion tanks. Consider hiring a local boiler installer to add an expansion tank, ensuring a high-quality and long-lasting placement.
If you’re worried that your expansion tank is in the wrong position, there are several signs that something has gone wrong. Look for these clues, especially if they happen right after an expansion tank installation.
A completely upside-down tank: Some expansion tanks have the option to place them horizontally, but the tank should never be installed upside-down. That prevents the air from condensing properly
Leaks from a new expansion tank: A new leak could indicate an installation on the wrong part of the system or with the wrong connections, especially if it starts leaking immediately when you turn the boiler system on. If multiple leaks suddenly appear after a new tank installation, that could mean the tank is failing to do its job.
Misbehaving faucets: If you turn on your faucets and the water shoots out extra-hard for the first several seconds, then your system is over-pressurized. One cause is a malfunctioning expansion tank that isn’t allowing the proper contraction and expansion of air. This only applies to boilers that also heat water for heating.
Rapid (and dangerous) pressure increases: If heated water doesn’t have any place to push extra air, then it will quickly raise the pressure of the boiler into the danger zone. If you see the pressure gauge showing alarming signs, shut it down and consult a boiler professional.
Malfunctioning bleed or relief valves: Bleed and relief valves normally bleed out excess air from the system. But if these valves immediately leak water without bleeding out air, the expansion tank likely has an issue.
A dull thudding sound: Give the tank a rap with your knuckles when the boiler is turned off. A healthy expansion tank should have a clear, hollow sound, showing that it’s filled with air. If the tank has a dull thud instead, it may be filled with water and not working properly.
Alarming cracking noises: When a boiler system can’t deal with pressure properly, the pipes and pipe joints suffer the most. This can create alarming popping and cracking noises, especially once the boiler is turned off and the pressure on the pipes eases.
I play a yearly service fee to get my heat and AC checked out, twice a year. It's awesome. The techs are always great.
CJS Heating and Air ColumbusChaz, the owner, was very responsive and he communicated with us throughout the entire process. The overall cost was in the middle compared to the three estimates we received. The installation crew was very professional. Chaz was considerate enough to send a crew back to our home to repair...
Unique Hardwood Floor LLCI've used Quality Drain Solutions multiple times and they are consistently excellent in terms of their level of service and quality of work. They respond quickly, arrive when they say they will, and clean up when they're done. They removed the leaky water heater, and replaced it with a new...
Quality Plumbing & Drains Inc.They unclogged the drain and sent me a bill for more than 4 times what I paid before. I called the Water Works to ask why the bill was so high and that they should have gotten my authorization before assuming they could make expensive decisions like that on my behalf and for their benefit....
The WaterworksI was called back immediately when I contacted this provider on Angie's list. Robert called ahead and arrived when he said he would. After looking over the appliance, explained what he thought the problems might be and worked on them. He fixed the problem at the bottom of the freezer that...
Central Ohio Appliance Repairthey sent a Heating Tech, Donnie to check out our furnace. He was courteous and very knowledgeable and very skilled in his trade. He thoroughly checked every aspect of my heating system and gave me suggestions to keep things working properly. He told me that the filters were still good and...
Best Service Heating & CoolingGreat!, Was able to get them to show up within 2 hours of calling, which was very much needed. Had a new refrigerator delivered that could not be installed. The main water shut off to my house and the shut off to the old refrigerator could not be turned off. Water was leaking everywhere...
A Mann Plumbing LtdEverything was great. They installed a new motor on a Wednesday and it heated ok for a day, which they did not charge me for. They came back out on Saturday and said that it was admitting Co2. They had to shut it down for safety. They made an appointment to come out Sunday. They made an...
I took the part to 3 mechanics to have it installed. One would not do it because of insurance reasons, one wanted want too much money to do the work, and the third recommended Arrow. Arrow installed the part for minimal cost, on the promised day, and the heater works great. They are an...
Aarrow Radiator & Auto GlassFrom average costs to expert advice, get all the answers you need to get your job done.
Looking to replace or upgrade your water heater? Use this water heater replacement cost guide to see what the work will cost and what factors affect your total.
Tankless water heater costs in Columbus, OH depend on the size of your water heater, location, fuel type, and more. Keep reading to calculate your expenses.
While solar water heater costs are a bit higher than a standard system, this energy-saving option could pay for itself in a few years. Here’s what you need to know.
Not getting enough hot water? Here's how to check the hot water heater for problems and what you can do to fix it.
The average lifespan of water heaters is 6 to 15 years for conventional models and up to 20 for tankless ones, but it can be less if they are not properly maintained.
Discover all the tankless water heater pros and cons you should know. Learn how these energy-efficient systems can save you money and space while considering their limitations.
