How much maintenance does an air or ground source heat pump actually need? This is a tricky question to answer when asked by our clients because the answer “in theory” is none. That’s right. If the life expectancy of your heat pump is 10-15years you could literally turn on and forget about it for all that time and it would happily work away providing you with heat. This is because there are no consumable parts within a heat pump. There are no burners or ignitors that will need replaced. There is no build up of soot and the temperature will always remain relatively low on all parts of the heat pump which limits heat strain.
The hardest working component of any heat pump is the compressor. The compressor is the heart of the heat pump, compressing and circulating gases around a closed loop. The modern-day heat pump, uses what known as a “scroll compressor”. The scroll compressor has 70% less moving parts than the more traditional “hermetic compressor” which you can find fastened on to the back of your fridge. To this day, I have still never come across a failed compressor on a heat pump…Not yet.
So why do I still recommend an annual service? To name a few reasons….
1. Heat pumps are usually installed using an unvented system heating and hot water system. When the water is heated, it expands and the components such as the expansion vessel and safety relief valve are there to avoid the water pressure reaching dangerous levels. Its strongly advised that these are checked annually to ensure they are functioning safely.
2. The evaporator and fan condition are to be inspected (Air source only). The evaporator is the thing that sits outside, and the propeller pulls air through its fins. The heat from the air is then absorbed by the heat pump. Blocked or damaged evaporator fins or damaged propeller blades will reduce the air flow. Reduced air flow results in the heat pump absorbing less heat from the air which results in low efficiencies and in the worst-case scenario, the evaporator will freeze up completely. I have personally come across a dead bird wedged into the back of an evaporator coil. Still not entirely sure what it was doing back there. Perhaps it was appreciating how well the heat pump had been installed.
3. External pipework or the ground loop need protected against frost. An effective way to throw money away is to let your ground loop or external air source unit freeze up. You may have had a frozen pipe in the past and your thinking to yourself, it wasn’t that bad. Well feel free to dig up your entire 50-meter ground loop or pay hundreds of pounds for a new heat exchanger (which may require a F gas qualified engineer). Split pipes and a voided warranty can easily be avoided if the antifreeze mixture is kept to the right levels. Antifreeze should protect against no less than -15 degrees C and at a PH of 7.
4. Printed circuit board and electrics. Especially PCB’s located on an outside unit should be checked. I have heard of a PCBs blowing due to snails on the circuit board. I am pretty sure the heat pumps warranty wont cover damage by snails!
5. And finally, the warranty itself. Many heat pumps come with a 5 to10 year warranty. There is not a chance on earth the manufacturer will honour that warranty if that heat pump has been abandoned and neglected for years and years. Many manufacturers require proof of service by qualified personnel before a warranty claim can be made.
So, what do you do if the heat pump does breakdown? The most common faults on a heat pump is poor flow rate, usually caused by a block filter. Filters are really easy to clean and can be done by almost anyone. If a more serious fault occurs, calling the original installers is a good start. However, all too often this doesn’t resolve the issue. This is because it is easy to install a heat pump. Hang a couple of radiators, plumb in a hot water cylinder and connect the flow and return to the heat pump. Turn it on and job done. The installers have been paid considerably well and now they are off. A couple years on, a problem pops up and they just aren’t interested (or have disappeared completely). You could try phoning your local heating engineer or plumber and watch the colour drain from his face as he takes the heat pump cover off. Perhaps you should phone a refrigeration or air-conditioning engineer considering that much of heat pump is F gas based. Or perhaps you should call an electronics engineer considering the average heat pump printed circuit board is the size of a shoe box.
The person you need to call if your heat pump fails needs to have an extensive knowledge in heating/ plumbing, refrigeration/air-conditioning and domestic electrics and electronics. Where the hell will you find someone like that? I have personally been on a site where the manufacturer sent their own engineer out who admitted that he hadn’t any idea how the heating and hot water side worked because he only had a refrigeration background.
Here at Yarrow Energy Solutions Ltd, we do have the expertise. We can diagnose faulty relays or capacitors, we can replace motors and pumps and we can repair F gas circuits and components. Without being too boastful, we are rather good at what we do.