Urgent: Issues with the installation height of the hot water pump and the water storage tank

Is a self-priming centrifugal pump being used? Choose one with a large net positive suction head; hot water is prone to vaporization, and its saturated vapor pressure is high, which makes cavitation likely to occur. It’s best to install the pump below the liquid level.

It’s either a non-self-priming type or an ordinary hot water pump. Also, what’s the purpose of that water container?

Agree with the person on floor 2; placing it below the liquid level is one method. I don’t understand what you mean by the water container you mentioned – is it the container at the pump inlet? If that is the case, the height of the tank can be increased and the height of the pump can be decreased, thereby providing a static head. The purpose of all these methods is to increase the head at the pump inlet, so that the available net positive suction head of the system is greater than the required net positive suction head for the pump.

Cavitation! It’s useless to install a water tank; consider using an submersible pump instead

It’s possible that different places use different terms for it; I’m not quite sure what you mean by a water storage tank. If it’s the tank at the pump inlet, I don’t think it serves much of a purpose. The one we have in our factory is mainly used to avoid the hassle of filling the pump every time it needs to be started. Agree with the opinion above; consider a submersible pump.

The poster can check the saturated vapor pressure of water at 90 degrees Celsius as well as the amount of vapor remaining in the pump. Even a regular pump won’t work if it’s on the same level as the tank; moreover, your pump is installed above the liquid level of the tank. The flow of water occurs at first because the inlet pipe of the pump is still cold, and that’s not a problem. But once the hot water from the tank enters the pump, it stops working – cavitation occurs. The hot water pump in our facility is capable of producing water at 95 degrees Celsius. The bottom surface of the hot water tank is 4 meters higher than that of the pump; the IR hot water pump was used, and there were no issues with it. Your tank is at a lower level than the pump; even if you choose a pump with a low NPSH, it is likely not to work. It seems unlikely that you will be able to find a pump that meets your requirements. I suggest considering raising the elevation of the tank or lowering the installation height of the pump.

Deep well pumps could be considered; this involves digging a hole in the ground, placing the pump inside it, so that the pump is at a lower level than the hot water.

It’s better to use a submersible pump; it eliminates a lot of hassle, reduces maintenance costs, and makes operation simpler.

Dear Mr. Haichuan, compared to ordinary pumps, what other factors are taken into account when considering hot water pumps, in addition to the net positive suction head?

It seems that submersible pumps could be considered; those made of fiberglass are also a good option

All the hot water pumps I’ve seen are located below the water level in the tank. It’s better to raise the tank level; it’s simple and easy to do

One more thing: at first, it might still be possible to draw water using a water bucket, but over time the bucket will be filled with vaporized gas, and it will no longer be possible to draw any water out of it

What we collect is hot water coming from ordinary traps, at around 100 degrees. All the hot water tanks are buried underground; it’s not convenient to place hot water pumps below the liquid level, as this can cause the pumps to break easily. Do you have any good suggestions? Thank you