Putney Plaza

To Do

• Investigate current state of heat pumps and CHP
• Install heat meters and controls
• Confirm current operation
• Recommission
• Remote dashboards

Existing Documentation

• Existing Wiki (DPS/Thermal Integration)
• Mechanical Equipment Schedule
  

Air Source Heat Pumps

An initial survey of the roof top heat pump systems has highlighted some significant problems.

• No way to understand current operation, without any feed into a monitoring (SCADA) system.
• No alarming
• No performance monitoring
• At least one of the main circulating pumps to the heat pumps has never been wired up, making operation of the heat pump impossible since installation.

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  Roof top heat pumps

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  Roof top heat pumps

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  Unwired circulating pump to heat pump (i.e. heat pump has never contributed)

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  Heat pump control panel

Next Steps

1. Obtain all relevant manufacturers instructions on heat pumps and fitted controls
2. Upgrade controls with open control system and remote monitoring so that the heat pumps can be setup and controlled as required
3. Recommission heat pumps using new system
4. Monitor performance and setup alarm routes

Issue with Internet Connectivity

The site has been plagues with internet connectivity problems resulting from changes in internet provider.

Key lessons learned from the experiences include:

• You only require standard simple internet, with no fancy management. A standard domestic connection is perfect.
• Routers should have the standard functions including:
  • Remote access via either http or https
  • The ability to setup port forwarding
• A fixed IP address is preferred. Dynamic DNS services can be used instead, however there may be occasional loss of connections as IP addresses update when they change.
• With engineer rates in the £100s per day, changing an internet setup to save a few pounds is a false economy that requires an engineer to attend site and reinstate port forwarding rules etc.
• Routers should be safe from tampering and accidental damage. A locked BMS cabinet is the preferred position.
• Where internet is not already available as per preceding points, a GSM modem should be included in the initial fit. It is common for phone lines and internet providers to take weeks if not months to get everything in place. Connectivity should be available from the first day on site.

September - October 2022 Plan

• Get internet to panel Completed 26/09/22
• Confirm readings from 4 new boiler sensors Completed 26/09/22
• Obtain remote access to new Internet Router
• Install VPN
• Add sensors to CHP (flow / return)
• Install new MQTT services into cloud server using Docker (data send directly to server) Completed 26/09/22
• Install Grafana and update cloud server dashboard and wiki with new data
• Regain control over boiler valves from new panel.
• Update controller in tank room for buffer/boiler control, and replace buffer sensors. This will provide renewed monitoring and control over the boiler circuits.
• Update sensors in each buffer tank Rewire boiler demand switch
• Fit a control panel on one of the roof tops, a well as a board inside the existing control panel. The new panel will be used to collect data and establish permanent requirements that will then be implemented via existing panel. We need to better understand what the existing panels wire to, then rewire sensors and outputs to the new controller to reinstate operation.
• Once one heat pump is working and visible, the others can be addressed.
• Reinstate heat meter when boilers ready for a workout
• Fully commission boilers and valves  
• Update boiler pump to a Magna3D for variable speed control.

Boilers

Measuring Boiler Outputs

A Micronics Clamp-On Heat Meter has been temporarily installed onto boilers in order to confirm the peak outputs of each boiler.

U1000MKII_WM_Issue_1.1

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  Micronics heat meter

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  Micronics heat meter flow measurement

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  NTC temperature sensors are also attached to the boiler flow and return pipes, both into and out of the header.

Wiring New NTC Sensors

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  The boiler controller initially has four NTC sensors attached. We use the Wiring Editor to create the wiring diagram to match the installation.

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  In the wiring editor we give each sensor a Device (boilers) and a Key (tF, tR, tIn & tOut). The NTC charts are already loaded into the symbol used in the wiring diagram.

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  The wiring diagram is processed and the JSON output is copied to the clipboard.

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  The JSON configuration is pasted into the controller's Node-RED and the flow is deployed.

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  Moments later, data can be seen coming through to the clients online server.

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  Temperatures can now be graphed.

heatweb_putney_zcc1.json Boiler Controller
heatweb_putney_heat_meter_1.json Heat Meter

Initial Findings

As part of the upgrades we are moving the client interface into Grafana. The image below shows the initial dashboard created to show the boiler temperatures.

Viewing the data highlights 2 things...

1. We have data resolution higher than needed, with every reading coming through, almost every second. This uses up more SIM data than needed, and results in graphs taking longer to load, with a vast number of data points to load if looking at a few days data. To correct this we placed a "Report By Exception" rule, whereby data is only sent every minute, or if it changes by more than 0.5C since the last send. This way, when there is little movement in temperatures we get a data point every minute, but when temperatures change rapidly, we get higher resolution (down to every second) so we don't miss anything interesting. The difference can be seen in the graph, looking at the orange System Flow reading, where the change results in less data points.
2. The System Flow temperature is nearer the return than the blow from the boilers. This means that the system flow rates are roughly double the boiler flow rates. This causes unnecessary mixing and we lose the higher boiler temperatures. It is clear that the method of controlling pump speed needs examining, potentially introducing pump speed control and tying it in with boiler sequencing.