The saga continues. I’ve previously documented the behaviour of MMAXX Ltd, the numpties (UK coll.: complete fecking idiots) who installed our ground source heat pump. But more has emerged, for which read on…

Last November, the heat pump sprang a leak, losing up to 10litres/day of the heat transfer fluid (essentially souped-up – and thankfully non-toxic – antifreeze). We managed to persuade a local renewables company to come out and refill the system, and I then worked out how to top it off myself, so we limped along. There was no sign of a leak inside the house or plant room – the fluid is fluorescent blue, so we’d probably have noticed the addition to the decor.

So it was underground, at which point we handed over to our insurance company. And everything stopped. They appointed a leak detection company, who regrettably proved incapable of either detecting our address or of briefing their staff on what they should be turning up with. By then though I’d a pretty good idea of where the leak actually was: the short (3m) section connecting the outside of the house to the top of the borehole – that’s the only section with joints. I tried to get a contractor to come and excavate that pipework. No joy. We staggered through last winter and, once the ground had thawed out, our ever-obliging neighbour Ben and I set to with spades, and dug the bloody thing out ourselves. My guess as to where the leak was, was supported by the fact that, on removing the load of the overburden above the pipes, the leak slowed down dramatically. A good sign.

It took from last November to October to find a contractor willing and qualified to replace the pipe section. When they did turn up and we dug the final section out, we found that the leak was in fact exactly where I’d thought it would be and that it was caused – once again – by the incompetence of MMAXX: they’d installed two fusion joints directly back to back, without the needful allowance for thermal expansion. Over the years then, the thermal movement as the weather changed and as the feed and return pipes heated up and cooled down, caused the joints to spring, as they couldn’t expand to compensate for the temperature change. Basic stuff.

With the pipework replaced, and the system topped up and tested, there was one last job: replacing the now-corroded connectors to the internal pipework, consisting of a brine filter and a stop valve on the feed and return. That went well, and the contractor walked up to me with the two removed components. “Have a look at these”, he said.

The brine filter had some small junk in it, plus some loose plastic wrapping, which I recognised as being from the plastic sheeting that the heat pump had been wrapped in on delivery. Pure carelessness. Then came the kicker: the feed and return pipes from the heatpump to the outside are a standard 28mm bore. He held up the valve, and this is what we saw: a chunk of quartzite stone (local geology), restricting (at a guess) the flow by something like 60%.

Now, the heat pump has never actually reached what we thought its potential to be: persistent vibration and whining from the circuit suggested that it was having to try a little too hard, and the backup heaters were tending to cut in around 0ºC, rather than at the design point of -4ºC. Now we know why. 

It is very hard to come up with an explanation for this that qualifies as ‘mere’ incompetence and carelessness. Intentional action springs to mind  here(by the time the initial install was finished, I was already taking them to task for their failings). I did though manage to ensure that they never got their last instalment.

Another late discovery has come from two other issues: firstly, that our hot water needs a decent flow to trip in – showers work fine, but taps can be a bit hit and miss – and when we run the log burning stove with back boiler, it gets to a certain temperature, at which point the thermal overheat valve triggers, dumping all the hot water into the courtyard. It turns out that these are related: the thermal store has two flat plate heat exchangers attached: one to take the input from the stove and the other to extract hot water. Guess what? Yes, they connected them the wrong way around, so we’re trying to pull 40ºC hot water from a heat exchanger designed to take in water at 80-90ºc, and the converse applies to the other, which simply can’t cope with the incoming heat. Some extensive re-plumbing is now required. More MMAXX incompetence, were any further demonstration required.

After a great deal of pushing, we had MMAXX’s MCS certification suspended, and were about to take them to court: however they just shut the company down, and started up a new one, which I am informed they have done several times since, apparently just as disgruntled customers were closing in on them. One thing that this process has very clearly demonstrated is that the government’s MCS renewables certification scheme isn’t worth a damn, and that it’s nearly impossible to get them to take effective action against a cowboy contractor. It also demonstrates the fundamental mismanagement of the UK’s company registration scheme: anything that allows directors to simply bypass responsibility for incompetence and lack of care simply isn’t acceptable in any legislature that seeks to demonstrate its integrity. But then this is the UK…