4 minute read
Central Heating
Try to answer the following multiple-choice questions.
Q1 SCENARIO: A customer calls you out to a problem with their central heating system. They have been in the roof space and found it very damp and full of steam. You investigate and observe the feed and expansion cistern is blowing water out of the vent pipe and overflowing. At the same time, the float valve is running, and the water is being drawn. What might this issue be? Ans.
a The boiler is set too high
b The cold feed and vent are incorrectly connected onto the system
c The pump is set too high
d There is a blocked feed pipe forcing water up
Q2 SCENARIO: A customer has a problem with their central heating system not getting warm enough. It comes on but soon seems to go cooler. They have bought a new remote room stat and placed it in their lounge. In the lounge they use a log effect gas fire for comfort. What is the potential issue with their system? Ans.
a The room stat is within the same room as the gas fire and being affected
b The zone valve is not staying open when called upon by the room stat
c The pump is not wired in correctly and stops each time the boiler stops
d The room stat is faulty Q3 SCENARIO: The customer calls you out because their condensing boiler has not come on after a period of freezing cold night and day. Identify the common cause from the list below. Ans.
a The water pressure might have dropped off
b The condense pipe has frozen
c The boiler has frozen in their kitchen
d The gas has frozen
Q4 SCENARIO: A newly installed underfloor heating system is not providing the heat output as designed on one section/coil set within a solid floor. The client has had new carpets fitted since commissioning. What might be the issue? Ans.
a The system needs balancing
b The pump is too small
c Pipework might be airlocked
d The carpets are too thick
Q5 SCENARIO: A radiator is installed under a window. The top is wedged in below the sill and the bottom touching the high-level skirting boards. The room struggles to get warm even though the radiator appears to be quite a large double panel. Identify the possible solution? Ans.
a The windowsill needs to be higher
b The radiator is too big for the space and convection currents can’t circulate sufficiently due to the lack of air space top and bottom. Install a lower height radiator
c The skirting board is too tall and should be changed for one with a spider ladder
d The radiator is installed in the wrong location for the required size
Q6 You are installing a new boiler onto a system that has been installed for the last 30 years. It becomes obvious the system is very dirty and blocked. What steps must you now take to ensure the new boiler will meet the manufacturer's instructions/warranty?
a Install the new boiler and check what you have installed works
b
c Inform the customer that their system is probably in need of a complete replacement
Make sure that any power flushing is observed by the customer so you can charge for the extra time
d Say nothing and hope it all works, get paid and leave Ans.
Q7
a Identify the correct system if there is a floor area of more than 150m2 in a property.
Fully pumped system using a three-port mid position valve with separate time and temperature, plus TRVs Ans.
b Fully pumped system using 2x2 port valves with separate time and temperature
c Pumped heating and gravity hot water with timer and room stat
Q8 When replacing a defective radiator valve on a vented system, which method is the quickest correct method from the list. Ans.
a Create a vacuum by plugging off all outlets
b Drain down some of the system
c Drain down all of the system and get a power flush job as an extra
d Snatch the pipe across with plenty of towels laid down
Q9 What is the purpose of the fins on the back of a radiator?
a To create space between the wall for air to circulate
b To help with convection currents
c To help with radiation currents
d To help create a gap between panels when manufactured Ans.
Q10 Correctly identify the working method of a thermostatic radiator valve from the list? Ans.
a The valve will sense the water temperature and adjust.
b The valve will sense the air temperature and adjust
c The valve will sense the water flow on the flow and adjust
d The valve will sense the return water flow and adjust
