39 HPM 0413

HPM April 2013

WWW.HPMMAG.COM Got a story? Ring us on 01732 748041 or e-mail twood@unity-media.com TRAINING/TECHNICAL Technical helplines: ready for your call Martyn Bridges, director of marketing and technical support at Worcester, Bosch Group, reveals some of the topical questions to have been put to the manufacturer’s technical support department over recent months... I’m fitting a boiler into an airing cupboard upstairs. Is it OK for me to run the condense pipe into a rain water downpipe? Is there anything I have to bear in mind? You can do this providing the rainwater downpipe runs to foul waste and not a soakaway, but there are also a couple of things to watch out for. If that downpipe was to back up, due to a blockage downstream, it could back up all the way into the boiler. So an air break of some kind would be prudent to prevent this. You should ensure the air break is fitted externally in order to prevent water damage to the property should the downpipe become blocked. An air break must be installed in the 43mm pipework, between the boiler condensate outlet and the drainpipe, outside the property, to avoid flooding during adverse weather conditions. I know some boilers have an internal bypass. Under what circumstances would I have to use an external bypass valve? The purpose of an internal bypass is to help dissipate heat within the boiler during the pump over-run period at the end of a demand and help maintain a minimum flow rate through the boiler at all times of operation. Different manufacturers have different requirements, however, so no assumptions should be made that the same requirements apply to different boilers. The internal bypass is not intended as a substitute for an external system bypass. If the system design requires an automatic bypass to be fitted, then one should be installed and correctly adjusted to manufacturer’s instructions at a suitable point on the system. An external automatic bypass should be used if the flow around the system can be reduced, adjusted by the occupier or stopped by means of zone valves or thermostatic radiator valves (TRVs). The use of a correctly adjusted external bypass will help to prevent: • TRVs from either slamming shut or struggling to shut against pump pressure resulting in potential system noise issues • Spring return zone valves either slamming shut or struggling to open against pump pressure again resulting in potential system noise • System noise from high water velocity when most TRV’s or heating circuits are closed or satisfied • The circulating pump from experiencing excessive load due to high system resistance. Must I powerflush every time I fit a new domestic boiler? It’s a competitive market out there and the extra expense of a powerflush on a quote can be a deciding factor for some customers. However, it’s important to point out to your customers that not every system needs a powerflush; it’s your decision as the installer to determine whether it’s required depending on the condition and layout of the system. In some instances, where the system has been well cared for, a chemical cleanse and flush will be all that’s necessary. I’m installing two oil boilers together in a boiler room. I would like to use a common flue header – is it possible? Yes, but there are certain things you must remember. As you will be using a conventional flue, the plant room/boiler location must have adequate ventilation to the relevant British Standard. If the combined output is greater than 45kW, refer to BS5410 Part 2. I recommended that you request the services of a flue specialist who will ensure it is correctly sized and design the flue system to the requirements of the boilers. I’m installing a boiler in a garage and I’m thinking about adding additional frost protection. I know that some boilers already have a frost protection function built in, so is there any need for additional protection? Built-in frost protection associated with gas-fired boilers generally works off the boiler’s internal flow sensor. With Worcester’s boiler series, when the temperature at this sensor drops to 8°C, the boiler will run the pump. If the temperature drops further to 5°C, the boiler will fire until a flow temperature of 12°C is reached. This is designed to protect the boiler but will not protect areas of the system that are outside of the heating envelope. So how do you overcome this? You could fit an external frost thermostat in conjunction with a pipe thermostat and wire it back to the boiler. This will add additional protection for the pipe and/or equipment in the area in which the frost thermostat is located. As the pipework will be lagged, the addition of the pipe thermostat will ensure that once the pipework has received heat and the pipe thermostat set temperature has been achieved, the boiler will be turned off. This cycle will continue until the ambient temperature increases or the heating system is in operation. If the system is zoned, and you identify additional requirement for frost protection, you will need to wire your frost thermostat through the wiring centre so that the relevant valve is energised on demand. This will then fire the boiler, circulating heat round the system until the frost and pipe thermostats are satisfied. For this you may require more than one frost thermo thermostat. enquiry number 130 The new Honeywell Installer Assistant App gives you everything you need to commission Honeywell Sundial RF² wireless controls and ensures the customer has the set-up they want. It even e-mails you and your customer the information on the settings and the service date you have set. You finish the job and look good. Installer Assistant www.honeywelluk.com THE DOWNLOAD NOW enquiry number 318


HPM April 2013
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