Central Heating Inhibitor Testing

I recenly refilled my central heating system after completely draining down to install an automatic bypass valve and then a partial drain down to install a Magnaclean filter a bit later on, when the system was refilled I used Fernox F1 inhibitor (£18.99 per 500ml), as I didn’t know the volume of water in the system to meet the required minimum of 5% inhibitor per 100 litres of system water, and to be on the safe side, I used two bottles of Fernox, as you can not overdose the system, but this is wasteful and not to mention expensive.

In order to use the correct amount of inhibitor, I needed to find the volume of water and ‘spend to save’, so I bought a couple of inhibitor test kits, a Fernox Protector Test Kit for £23.46 and Sentinel x100 quick test for £4.99.

kits

So, why did I buy two test kits!

When the system was completely refilled I used Fernox F1, a few months later I decided to install the Magnaclean and needed some pipe fittings and inhibitor to top up the system resulting from the partial drain down, however, the merchant didn’t sell Fernox F1 only Sentinel x100, so I bought that.

Reading on a plumbing forum their was a suggestion that it was not a good idea to mix different manufactures inhibitor in the same system, I read this after I had already bought the x100 quick test kit off eBay.

I was refunded the cost of the x100 which was good of Plumb-It in Huntingdon, and bought Fernox F1 from another merchant and I also decided to buy as a long term investment a Fernox test kit.

As I now had two test kits, I thought I would see if the Sentinel x100 quick test would give an accurate indication of inhibitor strength of Fernox F1 as the x100 quick test kit will do two concentration tests for £4.99, rather than spend over £23, having said that, I can do 25 tests with the Fernox test kit, so it is cheaper overall, but as a DIY’r getting the x100 kit is more cost effective.

x100

Reading the hazard data sheets for x100 and Fernox, they contained the same chemicals and concentrations, Fernox F1 had one further component:

  • (Fernox & Sentinel) <2.5% Benzotriazole
  • (Fernox & Sentinel) 5% Sodium Molydate
  • (Fernox) Nitrilotriethanol

So I decided to test if the X100 kit would work in practice.

test1

Running some system water off using the vent on the Magnaclean, you fill the container to 1cm from the top and add two tablets, shake and then wait 10 minutes, the colour of the solution should then be compared with back of the x100 packet, if its the same yellow colour or deeper, its fine.

test2

Using the x100 test, the result appears my system water is of an adequate concentration.

The Fernox Inhibitor Test Kit was slightly more involved than the x100 test, but not difficult, the first thing to do was establish as baseline for your cold water which was used to fill the heating system with water.

f1

Filling the supplied container with 10ml of tap water, you add drops of the reagent and count the number of drops needed to change the solution from Blue to Orange.

blue
This is after one drop.
4 drops

To change my tap water from Blue to Orange took four (4) drops of reagent, shaking the bottle after each drop, this number will be subtracted from the drops total in the next part.

Washing out the container, I refilled this with central heating system water to 10ml as before.

f2
1 drop

One drop of reagent added.

9
Nine drops of reagent added.
nearly

Very nearly there.

39

After 39 drops, the solution changed to Orange, subtracting the baseline tap water 4 drops, means that 35 drops were needed overall, referring to the kit instruction, for Protector F1 at the recommended dose of 500ml for 100L of system water, a minimum of 9 drops of reagent is required to change from Blue to Orange, obviously, I’m well overdosed!!

This got me thinking of how I can determine how much water is in the heating system, the Fernox web site suggests that in a domestic system, volume can be estimated by counting the number of single panel radiators in a property and multiplying by ten. remembering to count double panel radiators as two single panels.

I have 13 radiators with 3 of these being doubles, therefore, using the formula above, this would be 16 x 10 = 160 Litres of System Water needing  just over 1.5 x 500ml bottles of Fernox F1.

To cross check this approximate value, I went the manufactures site for my radiators and found the data sheets, checking the sizes of my radiators against the Kw output of each one, this equaled a total of 10.87Kw, allowing that 1Kw requires 11 liters of water and adding a overhead of 25 litres for water in the boiler, indirect heating coil and system pipework, it worked out to 144.5 Litres of System Water needing just under 1.5 x 500ml bottles of Fernox F1.

The next time the system is completely drained I’ll use one 500ml bottle and then test to confirm if indeed it does need more than one bottle, once established I’ll sell the test kit on eBay.

Magnaclean Pro 2 Installation

Updated 19 April 2023

Note – Boiler replaced, however Magnaclean has been retained, Blog HERE.

MAGNA

Today (21 April 18), I decided to install a Magnaclean Pro 2 in my heating system which has a system boiler with hot water and central heating controlled using the ‘S’ plan design.

Magnaclean removes suspended solids (ferrous (Magnatite) and non ferrous) from the circulating water and traps them within the canister, this is then cleaned out at regular intervals.

The removal of these particulates will improve the longevity of the boiler and its parts, although my system water has been previously treated with inhibitor and ran clear during the drain down to fit this, these devices are installed when boilers are replaced in compliance with Building Regulations Part L , so I thought I’d bring it up to code.

The instructions specify that the Magnaclean is installed on the return to the boiler after the last radiator and before any system filling/pressurisation point, next to the boiler was a good location for me.

before

In order to make room for the Magnaclean to fit, the cold water filling loop needed to be raised.

drain

With the boiler power isolated, the case was removed to give more working room, a hoselok fitting was screwed onto the cold fill line and a hose ran to drain, I then isolated at the stopcock and drain the line ready for cutting the 15mm copper pipe and raising the whole assembly.

lifted

Cold fill raised and leak tested, the maximum height was governed by the length of the braided filling loop, the 22mm copper pipe nearest the boiler is the return and this has two marks 150mm apart indicating where the cuts need to be made.

I used the hoselok fitting on the return filling valve, and drained the heating system water opening a couple of upstairs radiators to break any vacuum.

pipe slice

Using a 22mm pipe slice it was fairly easy to cut the pipe, due to the restricted working space, I had to use pump pliers to grip and turn the pipe slice through some of its travel.

magnaclean base

The Magnaclean has a slip socket allowing the unit to slide over the pipe, then once engaged, the unit is lifted slightly so the inlet pipe engages allowing a nut and olive compression fitting to be made, I used jointing compound on both top and bottom olives before tightening.

The isolation valves are on the left, rather than the right, I had to use this orientation so I could easily access the isolation valves, I was going to use obtuse street elbows to form  a tight set in the return pipe, lifting the  Magnaclean clear of the flow pipe so I could operate the isolation valves, but this was way too much work for no real gain, especially as effective fluid flow is a function of the Magnaclean canister and not the valve orientation.

finished

Once the canister was pushed into place and the lid was tight, I closed the radiator vents and started to fill the system watching for leaks, the filling system pressure reducing valve is set for 1.5bar, so this was left open as I went round venting the upstairs radiators.

With the first round of venting done, I vented the Magnaclean and boilers circulation pump before turning the boiler on to heat.

This was followed by more venting until the majority of the air subsided, I isolated the Magnaclean and drained it so I could add 500ml of Fernox F1 inhibitor to the system, using the canister as a dosing pot.

As I only partially drained the system, (downstairs radiators are below the boiler so I only drained upstairs), 500ml should be sufficient to top up protection.

The installation went well with no leaks, and once the Magnaclean was proved to be ok, I registered the device online for the 10 year warranty.

I’ll post pictures in a few weeks of the Magnaclean magnet to see what it has picked up.

5 May 18 – Checked the Magnaclean and this is what it had caught:

magnatite

My Vaillant Thermocompact system was installed in 2003 and has 13 radiators piped in 10mm.  I’m very happy with the low level of magnetite retained and nothing was trapped within the lower filter housing, I’ll check this again in a years time, but so far so good 🙂