I bought an older house and there are 1 inch pipes running from my hot water heater, across the basement then up to the bathroom on the second floor. The pipe also goes a round-about way and there is a lot of excess pipe that can be removed. Needless to say, it takes a LONG time to get hot water in the bathroom and obviously wastes a lot of water. I want to reduce the 1 inch pipe to half inch, take out all the excess, and reconnect to the 1 inch pipe going up the wall to the bathroom. My concern is that I will lose pressure particularly in the shower. Thoughts?
Plumbing – Will reducing the size of a pipe running to the bathroom reduce pressure at the fixtures in the bathroom
hot-waterpipeplumbingwaterwater-pressure
Related Solutions
Pressure
In a system fed from a header-tank, the pressure depends only on the height of the tank. To increase pressure you have only two or three options:
- Raise the tank higher.
- Install an electric pump (these are often used for showers)
If your header-tank is filled from a high-pressure municipal supply, you would probably get better pressure from that directly but in most places this would be a large job involving extensive knowledge of plumbing and local laws or codes. Your existing pipework and fittings might not be suitable for high-pressure.
Flow rate
The rate of flow is affected by
- pressure
- diameter of pipe
- length of pipe
Half-inch pipe is usually adequate for sinks, basins, showers etc.
If all the plumbing in the image is 3/4", then I'd simply tee off as near the new faucet as practical. In the drawing, somewhere between the laundry and the kitchen.
If you're worried about losing pressure to the other fixtures when the faucet is on, then you'll want to tee off using a 3/4" x 3/4" x 1/2" tee.
That way you'll have 3/4" all the way to the kitchen, but the supplies to the new faucet will only be 1/2". This configuration will help maintain pressure to the kitchen, when water is being drawn from the new faucet.
You'll want to install "anti-siphon frost-proof sillcocks".
These have a vacuum breaker built in, so water won't be pushed back into the plumbing. Without this feature, you could potentially contaminate the water supply. This is required by code in some areas.
The frost-proof feature should prevent the plumbing from freezing during the winter. The sillcock has a long stem, so the water is actually shut off way back where it connects to the plumbing, instead of right at the spigot. This means that when the valve is closed, there should be no water in the entire assembly. Basically, the water is shut off back inside the warm house, instead of outside where it's cold. NOTE: If you have a hose attached to the spigot, make sure the hose drains after each use during the winter.
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Best Answer
Reducing pipe size will certainly reduce the amount of cold water sitting in the pipe, but it will also reduce the pressure at any given flow .vs. an equivalent larger pipe. However, you are proposing to shorten (and likely remove some elbows) from the pipe as well as change the size, and then it's very much "it depends" - there are online calculators for pressure drop you can use to compare options, for instance, but they would need type of pipe, length or equivalent length (where each elbow counts for extra equivalent length) pressure and flow to calculate a result.
How much that's an issue will depend on the type of pipe (smooth plastic flows much better than lumpy corroded galvanized iron) the supply pressure, and the demand at the end of the pipe.
It sounds like replacing all the pipe is not convenient. If it was, then 1/2" PEX "home runs" have a considerable benefit since they flow pretty well but have low volume. If this is galvanized iron or the like, and feeding only the one bathroom group, I would suggest 3/4" PEX for the easily replaceable (and shortened) part unless you live in one of the places with absurd plumbing restrictions against modern plastic pipe.
If the pipe is 1" to supply many other groups (other bathroom(s), kitchen, laundry), then think carefully about where it makes sense to have 1" pipe (due to large flow demand) and where it does not.