What Size Pressure Relief Valve For Water Heater?
We may earn affiliate fees for purchases using our links (at no extra cost to you).
One cannot overstate how crucial it is to have a correct size pressure relief valve for a water heater.
If you want your water heater to work properly and efficiently, it is the first thing to do.
Both replacement relief valves and brand-new vessels fall under this.
However what size pressure relief valve for water heater is deemed to be perfect? Well, it depends on a few factors. Let’s get into it.
What Size Pressure Relief Valve For Water Heater?
Look for the maximum permissible operating pressure (MAWP)of the heater. The attached nameplate on the heater will tell you about this.
In the same way, the valve’s tag contains the pressure allowable for the valve.
But the valve rating cannot exceed a maximum of 150 PSI irrespective of the capacity of your water heater.
Available Size Of Pressure Relief Valve For Water Heater:
The consideration here is very simple. There is no standard size for any given water heater. So, considering the valve and heater rating, the list can be like this.
| Heater Rating (MAWP) | Valve Rating |
|---|---|
| 125 PSI | 125 PSI or Less |
| 150 PSI | 150 PSI or Less |
| 160 PSI | 150 PSI maximum |
What Is The Pressure-Relief Valve On A Water Heater?
In actuality, the name is really straightforward. This is literally a safety valve for the water heater. It reduces or controls the excessive pressure in the water heater tank.
In other words, it doesn’t let the water heater tank to burst from excessive heat.
If it isn’t for the pressure-relief valve, we would be hearing about a lot of blasts, and house or property flooding. Thanks to the valves, an engineering blessing.
So, in simple words, for your water heater, a valve is an unnoticed, nevertheless, crucial safety feature.
Why Is Valve Size Important?
Why does the size of anything important? Now you have the answer. If the valve size is not accurate, it risks the safety of the tank.
As mentioned earlier, the valve size has to be equal to or less than the heater rating.
For instance, if the nameplate of the heater reads MAWP 150 PSI, you should have a valve that is below that rating or equal to that rating.
So, the valve may have a 150 PSI or 145 PSI rating.
Adherence to the rule will ensure the needed pressure release. However, there are water heaters with a MAWP of 160 PSI.
But according to the industry standard, the valve shall not exceed 150 PSI. So, for a 160 PSI MAWP, the valve rating shall not be more than 150 PSI.
Note that, the pressure is usually less than 100 PSI inside the tank. When it exceeds this number, the problem begins to occur.
How Does A Pressure Relief Valve Work?
Basic physics tells us that when you heat something, it expands. The same happens inside your water heater tank.
When you heat the water inside the tank of the water heater, the water simply generates steam and starts expanding.
The more you keep heating the water, the more it expands.
Elementary physics also tells us that an expanding substance inside anything puts pressure on the surface of the host.
So, water will put pressure on the tank surface. The crucial point here is that you cannot always control the pressure by regulating the water temperature.
Some excessive pressure may not cause any harm. It will essentially make its way out using the water pipes.
These pipes are directly linked to the heater. But what if the pressure is too excessive?
This is where the pressure relief valve on the heater comes into action. The high pressure triggers the pressure relief valve.
It then gradually releases the hot air and water from inside the tank. So, the pressure lessens.
Once the pressure is down to the usual range, the valve stops working. Thus, it ensures the safety of your tank and prevents the home or property from flooding.
Test Your Pressure Relief Valve:
We should usually clear out our water heaters at least 2 times every year. So, at the same time, it is safer to test the pressure relief valve.
Since it will only take you approximately 10 minutes to do each of these maintenance activities, it makes sense to group them together.
First, place a large bucket beneath the valve, to begin with. Make sure you’re wearing protective clothing because throughout this procedure you’ll leak some hot water.
This clearly poses a danger of scorching. Disconnect the pressure valve’s drain pipe.
Now, you have to let the water run to the bucket out of the valve. So, lowly raise the switch on the valve. Push the switch only partially up for the duration of this test.
FAQs about what size pressure relief valve for water heater:
Does The Length Of The Pressure Relief Valve Matter?
Yes, the length of the pressure relief valve matters a lot. It ultimately determines how efficient the contract the valve has with the water. So, a longer valve is okay, but a shorter one is never acceptable.
What Size Thread Is The Pressure Relief Valve On A Water Heater?
A 3/4-inch NPT or National Pipe Thread works perfectly for most of the pressure relief valves for the water heaters. So, check it out and buy one of this size.
Can You Use PVC For The Water Heater Relief Valve?
No, the hot water building code doesn’t approve PVC. It takes a lot of time to release the valve. So, it is unsafe, and you should avoid it.
Are Water Heater Pressure Relief Valves Adjustable?
No, they come with one fixed capacity. So, you cannot adjust them. The usual size ranges from 120-150 PSI. Choose a valve that matches the PSI capacity of the water heater.
Why Does A Pressure Relief Valve Fail?
Due to rust and corrosion accumulation inside the tank, the valve frequently becomes stuck or becomes locked in position.
Alternately, the valve may be jammed as a result of a previous hot water discharge. The valve size has nothing to do with it.
Final Words:
As you already know what size pressure relief valve for water heater and what factors influences its size, you are good to go.
So, once you have an accurate capacity pressure relief valve, you are good to go. You can enjoy a warm bath with utmost safety.
