A water leak or flood in the plant room or boiler house is probably something a facility manager worries about the most – particularly as most water damage is preventable with the correct control measures. Resulting system downtime, the clean-up, replacement of damaged equipment, insurance company interaction and possible re-tendering of contracts all take time.

Sometimes you will be given advanced notice that a leak might occur – such as water weeping from a valve – other times you might notice quantities of water on the plant room floor.

If you notice these signs, quick and early intervention is crucial.

Water system valve leak

This video shows the service engineer performing heating service and maintenance inspection in the plant room of an office building. The engineer discovered a lot of blank caps missing from valves, including one such example where water was weeping from one of the valves – meaning the valve seal was passing.

Blank caps

Blank caps or blanking caps are one such preventative measure for a passing valve.

Blank caps are essentially small fittings that easily plug a valve, which prevents water leaks from occurring, should valve seals begin to pass or loosen over time – as they tend to do.

Blank caps are, for the function they perform and the peace of mind they provide to facility managers, extremely good value for money.

Fitting blank caps in this situation prevented any further water leaks, saving the building any downtime to heating services and providing the facility manager with peace of mind.

Blank caps in a water system


Any valve or opening in a heating or water system has the potential for leakage, therefore, it is important a plug is fitted – in this case, a blank cap. This is an extra line of defence after the mechanical seal on valves.

The valves shown in the plant room in this video are present to either act as a branch for future expansion of the heating system or they were initially used to fill the heating system.

Wider water/heating system – low loss header (LLH)

Further back from those valve connections into the pipework system were low loss headers.

The LLH is a type of oversized pipe with multiple connections that acts like a distribution centre for the heating or water system. Heating and water systems of one or more boiler or pump should have a LLH installed. This is due to the varying flow and load demands of the various boilers and pumps. It ensures the varying flow rates do not upset or damage the different pieces of equipment.

The purpose of the LLH is to allow the system to operate at its most energy efficient. It gives pumps the freedom to modulate, as demanded, the speed of water flow – without interfering with the boilers – further down the water system. It performs this by hydraulically separating water circuits.

The primary circuit travels from the boiler to the LLH and then loops back. The secondary circuit travels from the LLH to radiators, calorifiers, taps and other equipment – collecting heated water from the boiler via the LLH.

There are additional efficiency benefits to a LLH, assisting with service and maintenance of the water system too. When water enters the LLH, the velocity of water is reduced, allowing any dirt or debris accumulated in the system to drop to the bottom. Its built-in vent allows any trapped air to escape at the top, further assisting with efficiency.

This air or dirt in the closed system may originate from either corroded pipes or if mains water was introduced to replenish the system at some stage.

Consequently the LLH ensures desired temperatures reach radiators, under floor heating, calorifiers, air handling units and water outlets in all parts of a building.

The same process occurs in a cooling system, where a chiller is present as opposed to a boiler.

Low loss header in a water system

Preventative measures for a building facility manager

1. Install blank caps

Walk the plant room or boiler house and inspect valves for blank caps and any signs of leakage. If blank caps are missing, but there is no water present around the valve, the most cost effective solution is to contact a service company immediately and have blank caps installed. The blank caps may cost as little as a cup of coffee – depending on size – providing excellent value for the peace of mind and potential downtime saved.

2. Install a low lose header

If are extending your heating or hot water system, installing an additional boiler or adding underfloor heating, it would be prudent to add a low loss header, if there isn’t one already present. The LLH provides capacity for water systems to expand and for each additional service to operate at their varying and most energy efficient rate, without cross interference.

Thermodial’s approach

Thermodial’s approach is to set up a planned preventative maintenance (PPM) regime. This approach is the most risk averse, energy efficient and cost-effective measure.

Installing blank caps and low loss headers, monitoring valves for leakage and servicing all parts of the heating and water systems with regular maintenance service tests and checks to confirm their correct and efficient operation.

The implications of not having such a regime in place is evident from the video. Downtime to water systems because of time-consuming and costly repairs mean that a PPM regime will pay for itself many times over.

Explore our full PPM capabilities.