Common Issues with DHW Pumps and How to Troubleshoot Them

Running a commercial building presents its fair share of challenges, and keeping your hot water system in top condition is among the most critical. Domestic Hot Water (DHW) pumps are the unsung heroes of your setup, ensuring that hot water flows consistently and efficiently across your entire premises. However, like any mechanical system, these pumps can encounter occasional problems.

Whether you’re managing a hotel, office complex, care facility, or industrial unit, understanding common issues and engaging in proactive pump troubleshooting can save you significant time, expense, and disruption. Here’s a practical guide to identifying and resolving the most frequent DHW pump issues, plus tips on when to call in expert support from the team at National Pumps and Boilers.

Low Water Pressure: A Frustrating but Fixable Problem

Low water pressure is one of the most frequently reported issues in commercial hot water systems. It affects comfort, efficiency, and tenant satisfaction, particularly during peak usage times.

Why Low Pressure Occurs

• Blocked pipes or filters are limiting flow.
  
  
  
• An undersized DHW pump was unable to meet demand.
  
  
  
• Poorly calibrated speed settings.
  
  
  

How to Restore Pressure

Start by inspecting filters and pipes for any debris or sediment buildup. If the system is clear but pressure remains low, assess whether your existing pump is correctly sized for your building’s requirements. Many facilities benefit from installing a variable-speed DHW pump, which can adapt to fluctuating water demands more efficiently.

We’ve seen this firsthand: a multi-floor office building struggled with inconsistent pressure on upper levels. Upgrading to a variable-speed Lowara pump immediately resolved the issue and improved system balance across the entire facility.

Noisy Pump Operation: Diagnosing Unwelcome Sounds

Unusual pump noises, whether rattling, gurgling, or whining, are never a good sign. They often point to internal wear or system inefficiencies that require attention.

Common Causes of Noise

• Air in the system (leading to cavitation).
  
  
  
• Worn bearings or internal pump components.
  
  
  
• Loose fixtures are causing vibration.
  
  
  

Simple Fixes for Noisy Pumps

Bleed the system to remove any trapped air and install an automatic air vent to help prevent future occurrences. If the pump continues to emit strange sounds, inspect internal parts for wear, especially the bearings. Also, check all mounting bolts and brackets; loose parts can create unnecessary vibration.

We once assisted a hotel where guests were disturbed by a strange humming sound from the plant room. After tightening a few fittings and replacing a worn-out seal, silence was restored, proof that minor adjustments can have a major impact.

Pump Overheating: A Risk to Reliability

Overheating is a red flag that your pump might be overworked or improperly installed. Not only can it lead to shutdowns, but it can also shorten your pump’s life expectancy.

Why Pumps Overheat

• Blockages are causing restricted flow.
  
  
  
• Poor ventilation around the pump.
  
  
  
• Constant operation during periods of low demand.
  
  
  

Steps to Prevent Overheating

Check for obstructions that may be limiting water flow. Next, evaluate the pump's location; if it’s in a cramped or poorly ventilated space, consider rearranging the area or installing a fan. Finally, upgrade to a smart-controlled pump, such as one from DAB, which adjusts output to suit real-time system requirements.

Water Leaks: Small Drips, Big Consequences

Even a minor leak around your DHW pump can create major inefficiencies or damage over time. Leaks often originate from seal failures or cracked housings.

Causes of Leaks

• Ageing or worn seals.
  
  
  
• Loose fittings or poorly installed joints.
  
  
  
• Cracked pump housings or connecting pipes.
  
  
  

What You Can Do

Inspect all visible seals and tighten any loose connections. If the issue persists, replace damaged components with quality parts from our pump valves category. Addressing leaks early can prevent water damage, energy waste, and higher repair costs.

In one recent callout, we identified a cracked pipe joint in a leisure facility. A fast part replacement prevented potential flooding and downtime.

Airlocks in the System: The Invisible Blockage

Airlocks are among the most common heat pump problems. They restrict flow without visible signs, causing your pump to underperform or stop circulating water altogether.

What Causes Airlocks?

• Improper pump height or placement.
  
  
  
• Lack of effective air removal components.
  
  
  
• The recent system is draining without adequate re-pressurisation.
  
  
  

Fixing and Preventing Airlocks

Bleed the system using manual valves or install a Reflex automatic air vent for continuous protection. Ensure the pump is positioned at an optimal height, as improper installation often introduces air into the system. Regular system checks help catch this issue early.

Inconsistent Hot Water: A Common Complaint

If tenants or staff are experiencing varying water temperatures, the root cause may lie with your pump configuration or temperature regulation system.

Why Hot Water Supply Fluctuates

• Incorrectly configured pump settings.
  
  
  
• Faulty or ageing thermostatic valves.
  
  
  
• Pumps are not suited to fluctuating water demand.
  
  
  

Achieving Consistent Temperatures

Review and adjust pump settings to match building usage patterns. If your system struggles to maintain steady temperatures, upgrading to a model with intelligent control, such as one from Remeha, can make a big difference. Also, don’t overlook temperature sensors; they wear out and may require recalibration or replacement.

Complete Pump Failure: When Everything Stops

Total failure is among the most serious heat pump problems. Whether it's electrical or mechanical, it's crucial to act fast and diagnose correctly.

What Leads to Total Failure?

• Tripped circuit breakers or electrical faults.
  
  
  
• Motor burnout or impeller blockage.
  
  
  
• Severe wear from prolonged use.
  
  
  

How to Troubleshoot a Non-Responsive Pump

Start by checking your electrical supply, ensuring breakers are active and connections are intact. Next, test the motor and inspect the impeller for obstructions. For long-term peace of mind, you may need a full replacement. View our range of commercial DHW pumps from Ebara, Andrews, or Vaillant.

Why Choose National Pumps and Boilers for DHW Troubleshooting?

At National Pumps and Boilers, we understand the urgency behind restoring your hot water system quickly and efficiently. Our team of engineers has extensive experience handling both basic pump troubleshooting and more complex heat pump problems. We’re familiar with the full spectrum of brands, from Stuart Turner to Hamworthy.

Whether you need a quick fix, a detailed diagnostic, or a full pump replacement, our proactive approach helps avoid costly downtime and long-term issues.

Ready to Fix Your DHW Pump?

If your DHW system is underperforming or showing signs of failure, don’t wait. Visit our Contact Page to request expert assistance, or explore our full range of categories and brands for a solution tailored to your needs.

Let’s get your hot water system flowing properly, reliably, efficiently, and without disruption.