Mike - sorry to hear about your failed Grant HP.  Just wondering whether it can be repaired?  It wouldn't necessarily be usual to replace a gas boiler if one part fails...  perhaps parts aren't available or it has been unreliable and you want to change it anyway.

Just curious.

@editor have you ever investigated the repairability of the various ASHP brands?  I have a Mitsi and no idea how easy it is to repair.  perhaps the cost is prohibitive but if the mfrs made a virtue of providing spare parts it would be a consideration for me when selecting a new model and a positive move for sustainability etc.

@mike-patrick you absolutely have my sympathies. 

A couple of thoughts based on our experience.

First, I would strongly resist the temptation to simply swap the unit and hope for the best. That’s often the path of least resistance, especially if the existing pipework, controls and emitters are left largely untouched, but if the underlying design isn’t right, a new heat pump will simply inherit the same problems. I know you said yours wasn't a retrofit, but is there a chance that the design was still flawed?

Second, I wouldn’t read too much into the '10-year lifespan' point just yet. In theory these machines should last longer than that because they’re essentially refrigeration systems and compressors that, when operating within their design envelope, can run for many years. But if a system is poorly designed or forced to operate under constant strain (flow problems, high temperatures, cycling, poor hydraulics, etc.) that can shorten the life of the unit. Not saying that's the case for you.

Do you know why your unit failed Mike?

Your point about widening the search for installers is a sensible one. The key thing I’ve learned over the last few years is that installer competence varies enormously, even among manufacturers’ approved lists. If you do go down the redesign route, I’d be looking for someone who will start from first principles again... room-by-room heat loss calculations, emitter outputs at the intended flow temperature, pipe sizing, hydraulic layout and a sensible control strategy. I'm happy to recommend someone if we have an installer covering your postcode.

And again, sorry you’re dealing with this. Unfortunately your story is far from unique.

Posted by: @editor

↑

. If you do go down the redesign route, I’d be looking for someone who will start from first principles again... room-by-room heat loss calculations, emitter outputs at the intended flow temperature, pipe sizing, hydraulic layout and a sensible control strategy. I'm happy to recommend someone if we have an installer covering your postcode.

I agree but I would harvest the data available from the installation.  If nothing else it should be able to tell you what your whole house loss is.  Also your experience of different rooms may tell you about rad sizing and whether one or two should be upgraded.

But TBH first I would try to get the existing one repaired.  Just like a boiler, they dont necessarily need to be thrown out because one part has failed.

@downfield that's a really good question

From the conversations I’ve had with installers and manufacturers over the years, most of the mainstream units (including those from Mitsubishi) are technically repairable. They’re refrigeration systems at heart. Compressor, inverter board, fans, expansion devices, sensors and controls. In principle, many of those components can be replaced individually rather than swapping the entire unit.

Where things become less clear is the economics and practicalities of those repairs.

Some manufacturers are better than others when it comes to spare parts availability and technical documentation. Companies like Mitsubishi and Vaillant generally have established supply chains for boards, sensors, fans and compressors, and installers who are trained on those systems can diagnose and replace components. In other cases, I've heard that Daikin and NIBE have been criticised for poor availability of spare parts.

The second factor is labour and diagnostic complexity. Many heat pumps are heavily integrated systems with inverter drives, control boards and safety interlocks. If a major component fails out of warranty (for example the compressor or main PCB) the cost of parts plus specialist labour can start approaching the cost of a replacement unit. That’s often why you see installers recommending replacement rather than repair once systems get older.

The third issue is simply installer capability. Some engineers are very comfortable troubleshooting refrigeration circuits and electronics... others are more accustomed to swapping modules. The repair culture in the UK heat pump sector is still developing, and I can't see it improving for years to come. 

Your point about sustainability is important though. There’s a strong argument that manufacturers should make spare parts availability, repairability and service documentation a selling point. Long-term parts support, transparent repair procedures and reasonable component pricing would make a real difference, especially as the installed base of heat pumps grows.

It’s something I’m planning to dig into more later this year because homeowners rarely get visibility on this when choosing a system. Most marketing focuses on efficiency and output, not what happens in year eight or ten when something fails. 

Posted by: @editor

↑

The third issue is simply installer capability. Some engineers are very comfortable troubleshooting refrigeration circuits and electronics... others are more accustomed to swapping modules. The repair culture in the UK heat pump sector is still developing, and I can't see it improving for years to come. 

Your point about sustainability is important though. There’s a strong argument that manufacturers should make spare parts availability, repairability and service documentation a selling point. Long-term parts support, transparent repair procedures and reasonable component pricing would make a real difference, especially as the installed base of heat pumps grows.

It’s something I’m planning to dig into more later this year because homeowners rarely get visibility on this when choosing a system. Most marketing focuses on efficiency and output, not what happens in year eight or ten when something fails. 

FWIW the installer who put in my heat pump seems to do quite a lot of repair work including on 15 year old GSHPs.  I cant believe that he is unique so its clearly possible, obviously depending on the fault.  Some parts (eg the circulator pump) are essentially generic.

Posted by: @downfield

↑

 I have a Mitsi and no idea how easy it is to repair.  perhaps the cost is prohibitive but if the mfrs made a virtue of providing spare parts it would be a consideration for me when selecting a new model and a positive move for sustainability etc.

My Mitsi service engineer said that Mitsubishi only guarantee to stock replacement parts for my heat pump for 10 years.  If after that a part fails and they cannot source a replacement from within their universe then the unit is scrapped as unrepairable...at my cost to replace!   He did say that most parts are in stock for many years after the 10 year cut off but that some model specific parts that seldom fail can be the killer blow when they do.

Posted by: @abernyte

↑

He did say that most parts are in stock for many years after the 10 year cut off but that some model specific parts that seldom fail can be the killer blow when they do.

Same as many boilers, ovens washing machines and other stuff.  We live in a throw away society.

Fortunately many parts are common to several brands, often for decades, but when the PCB fails you have generally had it, unless you can work out which component it is in which case you can often source it.

@editor Yes, if you know of an installer in or near West Oxfordshire (Oxford/Witney/Swindon) that would be helpful. As the weather is now warming and we have alternative heating (wood burning stoves) there is no imperative to find an instant solution. I can take time to explore the options.

Mike

@downfield Yes, I'm going to look at repair.

Our local approved installer has had two people look so far. The first was a rookie who was doing some other plumbing work for us. He took photos of the ASHP and the control panel. The second came specifically to investigate further. The error codes on the Grant ASHP are predictably cryptic and he spent some time hunting down the main circulation pump before finally deciding it was in the ASHP unit itself - but not actually opening it up to view the pump. But his diagnosis was that it was probably the pump that had failed and at a replacement cost of £280 it was better to consider a new ASHP given its age! 

The firm has since emailed to confirm this and offered to send their "controls specialist" around (at £75 ph) to investigate the issue.

I'm not rushing in to this and will be calling Grant myself next.

Mike

@jamespa Our ASHP has a history and about 5 years ago we did have a new PCB, which cost then about £800. That was on the recommendation of a different local Grant approved installer. But based on what I have since learned I now believe that was just the easy route for him. The error code at that time was one that indicates a drop in system pressure. That's usually caused by a leak somewhere (we've had a few of those) which can be fixed easily. My journey with the ASHP has been a bit like owning a yacht - it's been a money pit!

Mike

Posted by: @mike-patrick

↑

@downfield Yes, I'm going to look at repair.

These systems should work fine without requiring the user to become a part time heat engineer and plumber. Unfortunately, visits from the "tech wizards" are damn expensive, and one tends to lead to another, then another... at some point it becomes profitable to invest the time to learn just enough to debug it on your own.

You can diagnose most of the issues yourself if you have a service manual, access to installer settings, and a forum with people willing to help.

Basically, if your heat pump is screwed, so be it. But maybe your problem is a clogged filter and all you need is a wrench and a toothbrush. No way to know from here.

For example, a pump problem is suspected, which means a flow problem is suspected. If there's not enough flow, or no flow, it could be a clogged filter or dirt separator, or a dead pump, or some debris stuck in the pump impeller, or a stuck pump in need of a firm turn with a screwdriver through the hole designed for this purpose, or a pump not receiving power, or a dead PCB, a blown fuse, or any number of other issues, some expensive, and some trivially cheap.

First thing to do would be check the flow sensor reading, enable the pump test mode so it runs, then check the flow sensor reading again, possibly changing the pump's setting in the test mode, see what happens. Then listen to the pump (some are so silent you need a stethoscope or feel the vibration with your hand on the pump). Then slowly close a valve in the primary circuit so it completely shuts off the flow, if there is flow you will hear the water hiss as the valve restricts flow. Also take a sample of the water from the dirt separator to look at it, if it's clean or not.

You also need to know your installation. For example, the guy had no idea where the pump is, which is expected. In this case, either you know where it is and things proceed smoothly, or you don't, and it'll probably cost you a few hundred more.