answersLogoWhite

0


Best Answer

materials tend to expand when they get hot, and that is true for sewer pipe material as well. Whether it's cast iron or ABS, the pipes will try to expand when they get hot and when they try to get longer they'll slide across wood or other materials. The "knocking" noise is the pipe fitting tightly against the wood and when the pipe has expanded enough it moves suddently and for a short distance, producing a "pop" type of sound. If you can expose the pipe you can cut out the wood where it is tight and possibly put in other material so that the pipe doesn't rub so hard.

User Avatar

Wiki User

βˆ™ 18y ago
This answer is:
User Avatar
More answers
User Avatar

Wiki User

βˆ™ 13y ago

That is usually called "hammering" and is caused by air pockets; it can be reduced by installing a device to arrest the air pocket. A DIY person can do this, check for the devices in a local home improvement supply company, they do not cost much.

This answer is:
User Avatar

Add your answer:

Earn +20 pts
Q: What causes knocking in drain pipes when hot water drains?
Write your answer...
Submit
Still have questions?
magnify glass
imp
Related questions

Features drains metal pipes etc?

The drain metal pipes are usually coated and galvanized because of the hard water.


What is an over flow drain?

They are secondary drains that work in tandem with the primary pipes to prevent overflows.


How do scorpions get in drains?

Scorpions can enter drains through cracks or openings in the pipes or through drain covers that are not securely fitted. They are attracted to dark, damp environments and may accidentally fall or crawl into drains while searching for shelter or food.


What cleaner is best for rust removal in drains?

Nothing dissolves rust in drain pipes. Once pipes become so old and rusty that they constantly keep blocking up, its time to replace and install PVC waste pipes.


Is there a product I can put in the drains to clear pipes of hairs?

Drain-o works very well. You can find this product at your local grocery store.


How do you clear blocked kitchen drains?

Clogged drains are caused by the accumulation of sticky material in the water pipes. Many times stuff like hair, food, plastic pouches.. gets stuck in the pipes and starts accumulating. Because of this the water from the kitchen or shower sink takes time to drain. Many times the drain pipes emit foul odor. Once the pipes are blocked, either the water stops draining from the sink or the debris starts coming out of the sink and toilets. The clogged water may also start leaking and also rust the pipes.[Source:A-General Plumbing and Sewer Service]


Who fixed water pipes and drains?

A plumber


When the toilet flushes it responds normally however after a few minutes the bowl drains completely of water there does not appear to be any leaks anywhere?

Check for a clogged air gap (the pipes that run from the large drain pipes to the roof of the house).


What metal is used to cover drain pipes?

Most drain pipes are made of copper


Who fixes problems with the drains and pipes in your house?

a plumber


Camera To Locate Drain Blockage?

form_title=Camera To Locate Drain Blockage form_header=8113 Are the drains clogged in other areas of the house when the water is turned on there?*= () Yes () No Why must a camera be used to diagnose your plumbing problems?*= [] Clogged or slow drain [] Suspect breakage in joints [] Suspect roots have penetrated pipes [] Suspect clogged pipes [] Inspection for a real estate transaction [] Other


Is something wrong when the toilet gurgles when the bathtub is draining when you are on a well and septic system?

When a basin drains and causes gurgling sounds in other basins -- or the toilet, in this case -- it is usually a sign that a vent pipe is clogged or obstructed. The air being displaced in the drain pipe of the bathtub has nowhere to go if the vent is clogged and is being forced up through other drain pipes.