How to install a vent for your tankless gas water heating unit.

A Guide to Venting a Heater

If you’ve done your research about tankless water heaters before purchasing one or planning to purchase one, you’ll know there’s two key types of tankless water heating systems or units. Firstly, there’s the more inefficient and power-hungry electric tankless water heaters, and then there’s the gas-powered tankless water heaters, which are far more efficient though will likely cost you a lot more than you expected to install.

Although, why? I mean, unless you’ve purchased a hideously expensive condensing gas tankless water heating system, you’re not going to require ventilation. But in the case of the vast majority of people, you’re certainly going to need to ventilate your tankless water heater to prevent carbon monoxide poisoning, and other unpleasant gases spewing into your lungs or the lungs of your husband or wife and or kids.

And unless you’re planning to put your gas powered, non-condensing tankless water heater outside, you’re certainly going to need that ventilation. It’s not a simple job, and can become quite expensive, which is why we’ve compiled this short yet snappy article for you to follow along with.

It’s complicated.

It is essential that we make this fact clear to you – if you’re not dexterous and aren’t good with DIY projects, we’re certain you’ll struggle to do this with ease. It’s a complicated job that can cost you a fortune – thousands and thousands and thousands of dollars – to put right if you get it wrong. For this reason, we strongly recommend with the greatest sincerity that you get a professional to come out and help you. It won’t cost you too much, unless there’s construction work involved, provided you’ve already got all the parts. These should be in the box.

Remember, there are two main types of venting – power venting and direct venting. Power venting will likely be much more expensive as it requires a pump or similar device, whereas direct venting just uses the laws of physics to allow the tankless water heating system or unit to release it’s exhaust into the atmosphere.

Some tankless water heaters can vent directly through the wall (which is helpful, as it removes the need for anybody to be taking anything away from the roof, although more traditional tankless water heaters designed many years ago will usually require rooftop venting. This can be quite un-attractive to home owners, as it can allow a lot of the cold and some of the elements into their homes through their roofs.

Decide Where the Vent Will Go

If you’re going with a wall vent, you’re going to have to decide where the vent will go. This will be a large piece of pipe simply sticking out of your wall, so ideally choose a location where it won’t ruin the view of your expensive, beloved house.

You need to choose this spot very carefully. If you mess this up, you’re probably going to have some very large repair bills, as you’re probably going to drill a massive hole into the side of your house for no reason.

If you’re uncomfortable doing this, we strongly recommend you force a professional in to help you. This will help you to prevent doing damage to your property, and encountering huge, unpleasant bills.

Begin Drilling

With ideally a 10-inch drill bit, once you have selected the ideal location for your vent pipe, you are going to need to drill a big hole in your wall. This should go right through to the other side, and should be visible from the inside.

Apply a lot of pressure and keep drilling to smoothen out any rough bits within the hole. This will help with attaching everything later on.

Useing a Template, Drill More Holes

The template you use will depend on the pipe you have, it’s circumference and its diameter. This template is nothing but a piece of plastic or metal with four holes.

Line up one of the holes of the template with the hole you have just drilled, and hold it in place there. Now, on that template you should see three or four other holes. Without moving the template, turn on your drill at high power and drill the remaining holes.

You should now be able to hold up your template and see it fully aligned with all the other holes in the template. If they don’t align, you’ve drilled something wrong and may have a problem on your hands.

However, if you have done it correctly, you can move onto the following step.

Make a Hole in the Wall

Now, drill through the wall, making way for a pipe. This may require some manpower, and may be very difficult. Ensure you take great care with this, as you do not want to rip the wall of your house to pieces in any case.

Thread the pipe Through The Hole

Assuming your tankless water heater has already come with the ventilation system it requires, you should assemble this ensuring the pipes go toward the hole in the wall as much as possible. Then, thread the pipe through the hole and into the outdoors. You have successfully connected your tankless water heater to the outdoor air, allowing for ventilation.

Seal any Gaps

Using a heavy-duty sealant, seal up the gap between the protruding pipe and the wall. You want to ensure that this is done correctly, otherwise the cold outside air can seep into and cool down your home.

You can also attach a breathable covering onto the end of the pipe to ensure no pests or bugs fly into the water heater and get burned.

The process is complete!

Congratulations, you have set up your tankless water heater’s venting system without the help of a professional!

About the author

Steve Bates

Hi, I'm Steve and I currently reside in Chicago, Illinois. Although for most of the last 20 years I was a partner in a HVAC company down in Austin, Texas.

I understand the frustration involved with dealing with water heater repairs and replacing or upgrading to a new, more efficient model.

My aim is offer some basic advice on fixing home hot water systems. And if a repair isn't possible, then to make the process of selecting a new water heater – be it gas or electric - as simple as possible.

So that you can save money and have a safe and reliable hot water system in your home for many years to come.