Last Updated: Friday, 24th November 2023
Single vs Twin Impeller Shower Pumps: Your Complete Guide
If you're looking to boost your shower's performance, you've probably come across terms like "single impeller shower pump" and "twin impeller shower pump." But what do these terms mean, and which one is right for you? In this straightforward guide, we'll break down the basics and help you make an informed choice.
What is a Single Impeller Shower Pump?
A single impeller shower pump is designed to boost the water pressure of one water supply only - usually the hot water. These pumps are often chosen because they can be more affordable and as such are a perfect fit for homes where only the hot water pressure needs a boost.
When using a single impeller pump to boost the hot water supply to match the mains cold water, it's really important to select a pump with a bar rating that matches that of the mains cold water as closely as possible in order to achieve a balanced flow.
Finally, while twin impeller pumps are the preferred method for boosting both hot and cold water feeds at the same time, single impeller pumps can also serve this purpose, especially when the feeds are located far apart. The key is to ensure that both single impeller pumps have the same bar rating.
What is a Twin Impeller Shower Pump?
Twin impeller shower pumps increase the water pressure on both the hot and cold water supplies. These pumps are a bit more expensive but offer a promise of a balanced flow and as such a good and safe shower experience.
Single vs Twin Impeller Pumps: Which One Do You Need?
The steps to understanding whether you need a single impeller pump or a twin impeller pump are simple:
Check Your Flow Rate
Measure your current flow rate across all the outlets you want to boost to understand your needs better. If your flow rate is less than 10 litres/min you definitely need a boost. Above 10 litres/min is considered acceptable, but you still may wish to boost this further. Read our article on measuring your flow rate to learn more.
Are You Boosting Hot and/or Cold?
The flow rates that you just measured will tell you if you need to boost one or two feeds. If it's one feed, you need a single impeller shower pump. If you need to pump two feeds, you need a twin impeller pump.
Don't forget that if you are thinking about installing a shower pump directly on the mains inlet that pumps more than 12 litres/minute, this is illegal. If this is the case, you will need to explore other options like an Accumulator Tank.
Are You in Positive or Negative Head?
Never forget this step. Understand if one or more of your outlets is in negative head or not. If your flow rate is worse than 2 litres/minute, you're likely in a negative head situation. In this case, you'll need a universal or negative head shower pump. Read our article on understanding positive and negative head to learn more.
Naturally, a twin impeller shower pump is more complicated and constructed from more material than a single. The likelihood is that a twin impeller shower pump will be more expensive than a single impeller shower pump, so if you're on a tight budget you may want to be smart about choosing a single impeller pump over a twin. However, if you have the budget, and understand the restrictions about pumping from the mains inlet, choosing a twin impeller pump will ensure water arrives at your outlets well balanced.
Check Out Our Shower Pump Buying Guide
If you've got any questions or need further clarification, don't hesitate to check out our comprehensive buying guide for shower pumps. Alternatively, you're always welcome to get in touch with us directly. We're here to help!
Frequently asked questions
What is a single impeller shower pump?
A single impeller shower pump is designed to boost the water pressure of only one water supply, usually the hot water. These pumps are often more affordable and are ideal for homes where only the hot water pressure needs improvement.
What is a twin impeller shower pump?
A twin impeller shower pump increases the water pressure for both hot and cold water supplies. These pumps are generally more expensive but offer a balanced water flow for a luxurious shower experience.
How do I know if I need a single or twin impeller pump?
Measure your current flow rate for all the outlets you want to boost. If only one feed needs boosting, a single impeller pump is sufficient. If both feeds need boosting, you'll need a twin impeller pump.
How do cost considerations affect my choice of pump?
Twin impeller pumps are generally more expensive due to their complexity and material. If you're on a tight budget, a single impeller pump may be a more economical choice.
Where can I find more information on choosing a shower pump?
You can check out our comprehensive buying guide for shower pumps for more detailed information.