Chemical testing

A method of dosing central heating system water with an inhibitor chemical, the method comprising the steps of:

• providing a dosing device, the dosing device including a fitment for permanently attaching the dosing device into a central heating system circuit, a chemical reservoir, a passageway in the fitment between the central heating system circuit and the chemical reservoir, a valve in the passageway, and a means for introducing chemical from the chemical reservoir into the central heating system circuit in response to an electronic signal,
• providing a testing device for testing central heating system water for inhibitor concentration, the testing device including a sample chamber for holding a sample of system water during testing, and a flow passage provided between the sample chamber and the central heating system circuit for allowing water to pass from the central heating system circuit into the sample chamber and back again from the sample chamber into the central heating system circuit,
• using the testing device to test central heating system water for the inhibitor concentration at time of sampling in a process which includes drawing a sample of water from the central heating system circuit into the sample chamber, testing the sample for the inhibitor concentration, and then emptying the sample chamber by returning the sample to the central heating system circuit,
• and if the inhibitor concentration at the time of sampling is insufficient, sending an electronic signal from the testing device to the dosing device, to cause the dosing device to dose the central heating system with inhibitor.