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How to Look

at a House


A blog with answers
to your questions about
HOME INSPECTION
and HOME MAINTENANCE


More Blogs about Plumbing:

  1. So the water heater is older...what’s the big deal?

  2. What are the most common installation problems with water heater replacement?

  3. Does a tankless water heater require a pressure relief valve?

  4. What are the pipes on my roof?

  5. Should I upgrade to a tankless water heater?

  6. How much does it cost to replace the plumbing in a house?

  7. How old is that water heater?

  8. What are the requirements for installing a gas appliance connector?

  9. Why is spray foam used for attic insulation?

  10. How do I get rid of the sewer gas smell in my house?

  11. What causes low water pressure in a house?

  12. What’s the powdery crust on the pipe connections at the water heater?

  13. Do you check the plumbing under the floor slab?

  14. What is a “cross connection” in a home’s plumbing system?

  15. What’s the flip-up handle on the water heater for?

  16. What is the difference between water service pipe and water supply pipe?

  17. My well water test came back positive for bacteria. What should I do?

  18. How can I tell what type of plumbing pipe I have?

  19. What is the difference between a regular water heater and a power vent water heater?

  20. How can I determine the age of a water heater if the serial number is missing or decoding it is impossible?

  21. What is a saddle valve?

  22. How do you test a shower pan for leaks?

  23. What is a grinder pump?

  24. What is that little tank on top of the water heater for?

  25. What are the minimum clearances around a toilet?

  26. What is the average lifespan of a water heater?

  27. What are the most common plumbing problems with older houses?

  28. Why are rubber washing machine hoses a safety risk?

  29. What is a dielectric union?

  30. What is a heat pump water heater?

  31. What are the common problems to look for when the plumbing has been replaced in a house?

  32. What is the average life expectancy of copper pipe?

  33. What is an escutcheon plate?

  34. Why is sunlight exposure bad for PVC pipe?

  35. What are the right words for talking about a house plumbing system?

  36. Should I seal the washing machine drain hose to the standpipe?

Welcome to our blog!
We want you to be an informed homebuyer, and each blog post is a question that we have answered for our friends and customers over the years. Hope they help you make a good choice for your next home.

   If the draft hood has been bent out of alignment with the flue opening at the top of the water heater (as in the photo below) or if there is any negative air pressure around the water heater—such as from the return air opening of an HVAC system nearby sucking air into it—then some of the combustion gases from the water heater may be drawn out at the draft hood opening, instead of additional air being pulled in. This is called backdrafting. It can also be caused by any obstruction or convoluted turns in the vent connector.


    Signs of a backdrafting problem are melting/buckling of the plastic discs around the pipe penetrations of the top of the water heater around the draft hood, as in the photo above, and corrosion around the opening due to moisture and acidity in the combustion gases that have been flowing over the top of the water heater, shown in the photo below.


   It is possible to demonstrate backdrafting when the burners are on by putting a mirror next to the draft hood opening and observing moisture from the combustion gases condensing on it, or by holding a match or smoke-generating device next to the draft hood to see the direction of the air flow.

   Because backdrafting means that combustion gases, including carbon monoxide, are not properly exiting the home, it is a safety concern should be repaired immediately. But the wrong solution is to simply remove the draft hood altogether, like the homeowner did the in the photo below.



While we hope you find this series of articles about home inspection helpful, they should not be considered an alternative to an actual home inspection by a local inspector. Also, construction standards vary in different parts of the country and it is possible that important issues related to your area may not be covered here.
©2015 - McGarry and Madsen Inspection.

 

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