Heating and hot water system

  • Background information

    The heating and hot water system at The Exchange is made up of several components, which need to work in sync with each other to deliver a reliable supply to your home.

    In simple terms, there are three boiler units, each with three individual boilers in the plant room for the estate.

    Those boilers generate heat and hot water that is delivered through a network of pipes to each home via a heat interface unit (HIU). There are also strainers at various points in the system, including in each HIU, to ensure debris from the water that drives the system doesn’t get into the mechanics.

    At the moment, six boilers across two of the units are operation, and can provide in excess of 100% of peak demand. This means that should we have unexpected failures of one or two boilers, the system will still be able to deliver all the heating and hot water you need.

  • Outages during October and November 2021

    The boiler units were automatically switched off on seven separate occasions between 28 October and 9 November. The first incident was caused by the main strainers in the plant room being blocked. Once those were cleared, heating and hot water were restored.

    The other six incidents since 29 October were due to the pressurisation unit in the plant room sounding a low pressure alarm which causes the boilers to shut down automatically. Normally, low pressure is caused by leaks. Although we identified and immediately fixed leaks following three of the outages, the pressurisation unit continued to sound the alarm and trigger the automatic shut-down of the boilers.

    On 9 November, we disabled the pressurisation unit and put in a temporary work-around to ensure the system continued to be topped up with water should the pressure drop. Between 8pm and 8am, an engineer was in the plant room to check that the work-around did what it needed to in the absence of the pressurisation unit and to check whether water was being drawn into the system as would be expected should the water pressure drop. None was.

    That suggested that there was a problem with the pressurisation unit, although it wasn’t displaying any faults. A series of diagnostic checks by the manufacturer didn’t identify any faults, but we decided to replace the unit anyway as we didn’t want to risk reinstating the old unit and having another outage. The pressurisation unit was replaced on Tuesday 14 December and BSW were on site to make sure it was working properly and in sync with the rest of the system. So far, there have been no further problems or false alarms.


  • Heat interface units (HIUs)

    We’ve completed a series of strainer cleans to the HIUs in your homes, which has resolved problems with heating and hot water in most cases. Please contact BSW if you still need your HIU strainer to be cleaned.

    We’d also reviewed 17 especially poorly performing HIUs and are reviewing the latest data to see if there’s more we can do.

  • Frequency of leaks

    There shouldn’t be this number of leaks and outages on a system of this age. The components on the heat network require oxygen levels to be carefully maintained, to prevent the lifespan of those components from being compromised. The volume of leaks has compromised some components, resulting in further leaks. The short-term remedial works (see below) should have resolved this issue.

  • Short-term remedial works

    In mid-September, before the October/November outages, we commissioned Fairheat to review the known issues at The Exchange. Their findings resulted in a short-term action plan to ensure you have a stable and functioning heat and hot water system over the colder winter months.

    We’ve now completed most of the short-term actions as planned before Christmas.

    We’ve brought back into service three additional boiler modules, which will double the number of available boiler modules and ensure peak demand can be fully met. We’ve also adjusted the boiler temperatures and the pumps so that they operate to maintain a constant differential pressure rather than continuously at maximum. That will improve efficiency and the life of the system.

    We’ve also installed a new water treatment unit and have scheduled regular sampling of the water so that water in the system remains clean and doesn’t interfere with the mechanics.

    In addition, we’ve removed debris from the system both in the plant room by increasing cleaning of the main strainers to fortnightly, and also by carrying out HIU strainer cleans in your homes.

    A report from a pipework and anchoring expert who visited The Exchange in early November didn’t identify any excessive strain on the pipework, so we didn’t need to have a rolling programme of planned downtime to install additional supports to the pipework as we’d initially thought we might.

    There are three actions remaining to complete the short-term plan. First, we need to replace the valves at the top of the risers. Although we’ve checked that those are closed, they sometimes let air in to the system. That causes air locks, which in turn result in localised outages. The replacement work will be complete by 24 December 2021.

    Secondly, we need to flush through the pipework, but we won’t do that until we’ve seen the new pressurisation unit work effectively for a few weeks. We now plan to carry out the flushing as part of our longer-term plan.

    Thirdly, we haven’t yet undertaken an extra check of the water quality by a third party as the various issues appear to have been resolved without having to do that at this point. We’ll now do that piece of work before we start the longer-term programme to provide extra assurance.

  • Long-term remedial works

    Using the data we get from the HIUs that were identified as poorly performing we’ll see if the issues can be addressed through a programme of recommissioning or if replacement is the best approach.

    At the same time that we either repair or partially/fully replace the HIUs we’ll reinsulate pipework serving the HIUs.

    We’ll consider upgrading the heat meters with more modern models that can provide remote identification of issues to enable our contractors to be proactive in addressing faults.

    We will replace all three boiler units in the plant room (nine boiler modules in total) with more modern equipment and replace some of the pipework to accommodate these new boilers.

    We don’t have confirmed dates for these pieces of work yet as we need to ensure that the short-term remedial actions have been successful first, but we hope to be able to complete them by the summer of 2022.

    We’ll continue with the water quality maintenance and monitoring regime to ensure the new boilers and recommissioned HIUs operate at the optimum levels.

  • Services from BSW

    Andy Lord, our director of compliance, has met the operations director at BSW on several occasions to raise concerns about non-attendance and call answering times (except where they’ve received multiple calls about the same issue). Andy has also shared specific feedback and details from residents, which has been acknowledged. Andy will continue to work with the team at BSW to address the concerns raised, in addition to regular contract review meetings.

    If you have any issues with the supply of heating or hot water to your home you should call BSW on 020 8763 5300. Their call centre is open 24 hours a day.

    We’ve reiterated to BSW that The Exchange is a site that requires a different type of fault diagnosis compared with a home with a traditional combination boiler. They recognise that and are ensuring their contact centre staff ask the appropriate questions to quickly and accurately diagnose the fault.

    If you need to escalate an issue with BSW, or have feedback on the service they have provided, please report this through MyAccount. If you are unable to use MyAccount you can also email us. We aim to deal with heating and hot water escalations on the same working day if you are experiencing a total loss.