Automated Water & Effluent Ltd

AWE Ltd Watermark

Boiler and Hot Water Dosing AWE Limited Autumn 2015 Watermark

Boiler & Hot Water Dosing

All the constituent parts for flow controlled boiler dosing including a dosing pump and a water meter.

As we are entering Autumn it's that time of year to think about boilers and LPHW (Low Pressure Hot Water) systems, and there are several methods that we cater for.

We covered chemical dosing pots in the Autumn 2014 Watermark, where we introduced the stainless steel chemical dosing pot. As an instrument and dosing company, our preference is to use a controller and dosing pump for this duty. For LPHW systems, there are several methods we are able to cater for.

Flow Proportional - for make up water where the line is fitted with a contacting head water meter, used to control a dosing pump with an external pacing control input. Simply do the sums involving the water meter K factor, the pump size determines the desired amount of treatment required in PPM (parts per million or mg/L).

conductivity control - where a conductivity cell is installed in the hot water pipework, ideally in a by-pass, so that it can be removed for maintenance and calibration.

The conductivity controller controls the corrosion inhibitor pump, so when the fresh water is added to the system, this dilutes the chemical concentration causing the conductivity to drop.

Switching on the chemical dosing pump to add chemical, increases the conductivity. The conductivity of the chemical reagent added must be considerably higher than the systems solution in order for this to work.

Timer Control 1

Either on a 7 day timer so inhibitor is added on a regular basis, e.g, every Monday and Thursday for 10 minutes per day.

Timer Control 2

By a shot dose timer where the service chemist analyses the water for inhibitor content and adds a known volume of reagent, by setting the timer to dose for the pre-set time, i.e. a 6 L/Hr dosing pump, set for a 10 minute shot dose will add 1 Litre of treatment. We are able to supply all of the above as a simple dosing stations with a bunded area for the chemical treatment drum.

Service Team Strengthened

Our service team has been strengthened recently with the addition of Eng. Andrew Lomas.

Andrew along with Service Manager Chris Michael and Engineers Gareth Hardwick and Bill Washbourne bring many years experience to Automated Water & Effluent Ltd.


We are able to offer routine servicing and calibration facilities on site, tailored to our customers requirements, whether it be a buffering service to maintain optimum efficiency of an effluent plant, calibration of your process line instruments, or certification of laboratory pH and conductivity instruments with traceable certification to national standards.

Enhanced Reputation

AWE is renowned for its after sales support and this is further enhanced by our specialist engineers continually attaining SafeContractor and Confined Space Working Scheme accreditations.

Already very active in the food industry for calibration and certification of our instrumentation, we provide national coverage for our complete range of products as well as in-house workshop repair and calibration facilities.

Technical Tips - Sensor Installation

We are often asked about the best way to install our sensors. Measuring the pH, Redox, or Conductivity in a flowing pipe is a common request.

First it must established if the flow is constant and the pipe always full or if the flow can be stopped and the pipe drained for maintenance.

If the process cannot be stopped then we have two options:-

1 - A Retractable Sensor like our lock-n-load which will be covered in a future article.
Feel free to get in touch if this describes your situation.

2 - A by-pass System A by-pass system needs to be installed at the same time as the pipework or during the plant shutdown.

A by pass system essentially consists of three valves in the line so the flow travels past the sensor or is diverted so that there is no flow past the sensor.

diagram showing how to install an inline pH sensor

A drain valve should be fitted so the pressure in the line can be relieved and the pipe work drained before removing the sensor (see drawing).

Before draining and removing a sensor please ensure that all the required health & safety precautions and risks assessments etc. are adhered to for you site conditions.

The sensor can then be removed, examined, cleaned and calibrated as required, or if a replacement pH sensor is required this can be fitted.

The sensor can then be refitted, please check that the drain valve is closed, and then open the valve to reintroduce flow past the sensor before closing the by pass valve, so as not to stop the solution flow.

Many of our pH and Redox Electrodes have a quick release union type fitting for easy removal without tangling the cables. Insertion Conductivity Cells have a demountable connector which can be removed to save disconnecting the cable.

inline pH electrode installed on a customers site

A typical installation of our PES-2-QR inline ph electrode system with quick release fitting, where the pipework cannot easily be drained for calibration.

We like to keep things simple - as the simpler they are, the more reliable they are.

The Grapevine 🍇

Recently, a regular end user customer of ours came to us with a problem with his polypropylene vee notch tank.

It was a strange shape and looking worse - for wear. On checking our records we had supplied this tank over 20 years ago with a flow meter, ph meter, recorder, and an automatic flow proportional sampler.

We know this customer has recently installed a heat exchanger to reduce the temperature of his effluent discharge and recover some of the wasted energy he had been losing down the drain.

So the original polypropylene vee notch has stood the test of time very well considering the elevated temperature it has been subjected too.

Vee Notch Tank for open channel flow

The customer required a custom sized vee notch tank, double quick, to fit during his summer shutdown.

This we were able to supply in time for his shutdown, and as part of the process involves the usage of detergents, the waste water can produce foam so the first compartment of the Vee notch tank has a bolt on lid (customer will bore a hole at the correct position for the inlet pipe). This will help to eliminate the foam in the chamber.

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AWE Autumn 2015 Watermark

The 2015 Autumn Watermark is available as a PDF or for printing or to read offline.

If you would like to receive email reminders when the winter watermark is published then please fill in your contact details on the Past Newsletters Page or at the bottom of this page.

A simple shot dose system mounted in to a dosing station with a bunded area.

Dosing station with bunded area for shot dosing a known volume of chemical into a low pressure hot water system

A simple timer controlled shot dose system is mounted with a polypropylene dosing station.

The adjustable timer allows the dosing pump to operate for a set period of time and with a known output, the precise amount of chemical can be delivered into the system.

This particular unit has a low level shutoff and alarm, so that the pump will not operate when a low level is present and user is alerted via an indicator light.

The bunded area is designed to all of the chemical should a leak in the container occur.

For more information on our systems or to discuss a custom dosing system please don't hesitate to get in touch on01785 254 597 or by emailing and we will be happy to discuss your application.

Automated Water &s; Effluent Ltd are proud to continually maintain our safe contractor approval.

AWELtd Safe Contractor Approval

Our onsite service personnel maintain professional standards and appropriately trained carrying both SafeContractor certification and are accredited for a variety of specialist working environments including Confined Space Working Scheme accreditation.

For more information on site servicing, commissioning, calibration, certification, or to discuss another service requirement please call us on 01785 254 597 or by emailing and we will be happy to discuss your application.

Contact AWE Ltd sales on 01785 254 597 for more information or to purchase our products.