Heat Exchanger

Cleaning your plate heat exchanger correctly and regularly will help you to extend the lifespan of the unit and ensure it continues to function properly. If you do not regularly clean and maintain your plate heat exchanger, you will find that the water pressure suffers, and the item will start to become inefficient and less reliable.

To keep your equipment running in tip-top condition you will need to take regular steps to ensure that the build-up of debris from the fluids flowing through the canal doesn’t build up to a point where they cause problems.

Most plumbers will not clean plate heat exchangers as it is just not worth it for them financially, so they will just replace them – you could do that too but if you like to have a little tinker, read on for how to clean a plate heat exchanger.

What is a Plate Heat Exchanger?

A Plate Heat Exchanger allows heat to move through its surface and transfer heat levels between two fluids that do not come into contact.

For example, you may want to transfer the heat contained in a hot fluid loop to a secondary loop, applying a plate heat exchanger between the two will allow this to happen without any contamination between the two liquids.

The exchangers are designed so that a set of parallel plates are positioned close enough to each other to allow fluids to flow in the channels created.

Hot and cold fluids then alternately flow through the plate allowing the transfer of heat from the hot fluid, through the plate to the cold fluid which is flowing alongside it.

How to Clean a Plate Heat Exchanger?

As a Plate Heat Exchanger is used, there will inevitably come a point when mineral deposits from the water begin to build up in the canals, affecting its ability to function correctly.

Instead of cleaning just the plate heat exchanger, you could flush your whole central heating system annually instead.

What You Need

  • Bowl
  • Towel
  • Fernox DS3
  • New Plate Heat Exchanger (optional)

Step 1 – Remove the Plate Heat Exchanger

So, your first step is to locate the plate heat exchanger and isolate it from the system. Then once the unit is isolated, you can remove it – keep your water bowl at the ready to collect any spillages.

Step 2 – Cleaning an Exchanger Plate with Water

Then use clean water to flush out the canals on the plate in the opposite direction to which the fluid normally flows, until the water exiting the plate runs clean.

If the build-up isn’t too bad, this may be enough. However, if the plate still isn’t functioning well, you may need to use a PHE-compatible cleaning agent to remove more resistant build-ups in the canal – personally, I use Fernox DS3 (amazon link – opens in a new tab).

Step 3 – Use PHE Cleaner

Next up, we will soak the PHE in Fernox DS3 for approximately 8 hours. This can be done overnight to save on waiting time.

Dissolve the Fernox in hot water and then fully submerge the unit and move about until you feel that there is no air left inside.

After approximately 8 hours, you will need to rinse off the unit with warm water until you are happy that the water is running clean.

Step 4 – Refit or Replace Unit

Now you can refit the unit although if the plate still isn’t functioning correctly and the pressure drop remains, you will need to think about removing the plate, stripping it down and cleaning it manually.

Note: In truth, fully stripping down a plate heat exchanger is rarely successful and even if it is, it will drastically reduce its lifespan. In this instance, it is probably best to just replace the unit altogether (amazon link – opens in a new tab).

Step 5 – Clean the Plate Heat Exchanger Manually

To begin the manual cleaning process, you will need to open the plate pack. For guidance on how to do this refer to the manufacturer’s instructions or contact them directly.

Once the plate is removed you should use the cleaning directly to the plate canals where you can see fluid build-up has accumulated.

Then use a high-pressure washer and a soft brush to help with rinsing off the cleaner and dirt. make sure not to be too strenuous with the cleaning as this can dislodge or damage the plates.

Once the plates are clear, then put the plate pack back in place and set the equipment running again. You should see a marked improvement in functionality.

Step 6 – Schedule the Next Clean

As you can see, as long as the build-up of fluid debris is not too resistant, cleaning plate heat exchangers is a relatively simple process.

Making sure that you check for debris in the plate canals and regularly clean the exchangers will save you lots of money in the long run.

So, note down when you cleaned the equipment and when the next cleaning session is due – every 12 months is a good guide to when this can be done.


Maintenance and regular cleaning of the Plate Heat Exchanger is not as involved or time-consuming as you may initially think. And if you follow the steps we have detailed above regularly, you will find that each cleaning session becomes quicker and easier as build-up between each cleaning process becomes minimal.

If you ignore the maintenance of this item, you’ll find that the water pressure drops, and the functioning of the plates becomes a lot less effective. And the longer you leave the problem without addressing it the more damaging the long-term effects will be.

So, you can replace the unit or save yourself the expense and disruption of replacing degraded equipment by increasing the life span of your current plates – the decision is yours.

Plumbing Wizard Tips

“Central heating cleaning and maintenance can save you time and £££’s in the long run!”

“If you decide to replace the unit, before giving it to the scrap metal man, have a look at it so you have an idea of how to clean one in the future!”

“Make sure you note which way round the heat exchanger was fitted. The direction of flow should already be marked but you may want to make some marks of your own!”

“Luckily, if you have an idea how to remove them, plate heat exchangers are quite straightforward to clean and maintain. If not, however, it may be best to call a plumber to do a full central heating power flush or to replace the unit altogether!”

Frequently Asked Questions

What can I use to clean a plate heat exchanger?

Fernox Ds3 is a product that can be used to clean plate heat exchangers. It is a top-notch de-scaler and cleaner that is designed for use on all types of stainless-steel equipment.
Fernox Ds3 is safe to use on all types of stainless-steel equipment, including plate heat exchangers. It is important to follow the instructions on the label when using this product and to allow adequate time for it to work before rinsing it with water.

How often should plate heat exchangers be cleaned?

It is good practice to flush central heating systems including heat exchangers at least every 12 months. The best time of year to do this annual maintenance is at the end of the summer before you start using your central heating systems again.

Are plate heat exchangers easy to clean?

Plate heat exchangers are relatively easy to clean although if they are too clogged even for a product like Fernox, the unit will likely need replacing.

About Me

I’m Lee the Plumbing Wizard. I’ve been a plumber for over 40 years and have seen it all. People used to call me a magician because I could fix things so easily – hence the name Plumbing Wizard.
I’m always happy to help out a fellow tradesman or woman, so if you need any advice or just someone to talk plumbing with, don’t hesitate to get in touch!

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