To Sleeve or Not to Sleeve. That is the question

I recently had a situation and following discussion regarding chimneys and sleeving water heaters after a new furnace was installed. I have several pictures attached showing different problems all relating to homes with a direct vent furnace and no sleeve (or chimney liner) installed to the existing water heater.

Pictures 1-2-3 are from the same home. The lining looks to be in good shape for the 5% that is visible. No rain cap, no sleeve to the water heater, visible water at the bottom of the chimney. Looking at the 3rd photo, there was some evidence of back-drafting in the past shown with the melted pipe insulation.

Picture 4 shows a badly deteriorated flue liner (a chunk has fallen and is wedged in the chimney) with a direct vent furnace and an originally installed water heater. This home was built in the 1970’s.

Picture 5 shows the top of the water heater where again evidence of back-drafting has occurred. Scorched top, melted insulators, etc. This water heater also vented to a chimney that was no longer used for the furnace.

If the chimney is no longer being used for any combustion appliance, I mention to my clients to consider removing the chimney at some point in the future to eliminate the maintenance that will be required at some point.

If the chimney is of original construction and designed for a water heater and furnace and the furnace is upgraded to a direct vent, the chimney size probably is no longer correct. This is the upper Midwest and we frequently see very cold temperatures (below freezing for months on end). Would this be a defect and the addition of a sleeve to the water heater be an option to be professionally evaluated and installed?





Hey thanks for posting these pics. We don’t see this setup much here. Its nice to see some of the indicators before I see and miss them!

Here are a couple more pictures from the chimney clean-out. Both pictures are taken from the basement (dumb comment since I wouldn’t expect a clean-out to be any other place on a single flue chimney :-)) of a two story home. Does anyone see a problem?

Both of these go along with the question stated earlier.



Yes, there are problems but you knew that.

The chimney is partially blocked and deteriorated and the connector pipe extends into the chimney too far and the water heater exhaust is condensing causing corrosive zinc oxide, etc. to bleed out from the pipe and it is backdrafting.

The cheapest fix may be to go electric with the water heater. A stainless steel liner may be the answer, too, but I would leave that up to the qualified professionals to decide.

I wouldn’t say I knew that, but I suspected a problem and referred it accordingly. When I asked my common question during the booking process “How did you hear about us?” He mentioned I was on a list from his Realtor but he did his research on the web and had decided to hire us even before he received the list. During the inspection I found out our client was the son-in-law of a local Realtor that I’ve worked with on occasion in the past. We’ve been hired by many Realtors and their family members to do their own inspections.

I had a great opportunity to help educate this Realtor during a follow-up call with the hopes of helping the importance and consistency of our industry. The feedback and comments from NACHI has been a tremendous help! Thank you!!

To answer your question I would definitely say that if you are using the clay chimney strictly for the gas water heater it would be oversized and should be lined with the appropriate size liner and as you stated be evaluated by a hvac contractor. For a water heater a 4 inch chimney liner is very typical.

About 1992 with the introduction of fan assisted venting of gas appliances the vent sizing tables for gas appliances have also changed to accommodate the changes in appliances and also addresses the type of construction of the home (air tightness)

Flue gas spillage can result from
1 most common blocked, damaged or deteriorating chimney or vent.
2 Spillage due to the vent of a natural gas appliance competing for air with other mechanical systems in the house or wood burning appliances. Pressure induced back drafting.
3 Spillage due to insufficient chimney draft because of poor chimney or vent design.
4 Poorly maintained equipment, cracked heat exchangers.