How to Change Your Filters and UV Lamp
Two jobs keep a filtration system working: changing the cartridges, and on a UV system, changing the lamp. Neither is hard. Both are done wrong often enough that we get the phone calls.
This covers both, in order, with the intervals that actually matter and the mistakes that cost people money.
The short answer
Every 6 to 12 months. Nearer 6 on tank or bore water, nearer 12 on town supply.
Every 12 months without exception. A lamp that still glows has usually stopped sterilising.
Replace the quartz sleeve at every annual service. It comes in the kit. Fresh o-rings every time the chamber is opened.
Before you start
Read this first
Turn the water off and release the pressure before you unscrew anything. Most Puretec housings have a red pressure relief button on the cap. Press it, or open a tap downstream, until the hiss stops.
On a UV system, disconnect the power as well, and let the unit cool before you touch it. The lamp runs hot and the chamber holds hot water.
Hand tighten only. Never use the spanner to close a housing.
Changing your filter cartridges
You will need the housing spanner that came with the system, a bucket, and the food grade silicone lubricant that comes in the maintenance kit. Nothing else.
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Turn the water off and release the pressure
Isolate the supply. Press the red relief button on the housing cap, or open a tap downstream, until the pressure is off. If your system has a plumbed bypass, switch it across now and the rest of the house keeps running.
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Unscrew the housing
Counterclockwise, using the spanner supplied. Have the bucket under it. The housing is full of water and it will come out.
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Take the old cartridge out and clean the bowl
Wash the bowl out. Check the large o-ring in the cap for splits or flat spots, and wipe the groove clean. A tired o-ring is the usual reason a housing weeps after a service.
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Lubricate the o-ring
A light smear of the food grade silicone from the maintenance kit. Do not use petroleum jelly or plumbers grease. They swell the rubber and they are not rated for drinking water.
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Fit the new cartridge
Seat it squarely over the spigot in the base. A cartridge that is not centred will let unfiltered water past the seal. Write the date and the cartridge code on the housing while you have the pen out.
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Screw the housing back on, hand tight
Hand tight only. Overtightening splits housings and it makes the next change a fight. If it weeps, the answer is a clean o-ring, not more force.
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Water back on slowly, then purge the air
Open a tap downstream and let it run until it stops spluttering. Flush for one to two minutes. New carbon sheds a little black dust on first use, which is normal and it clears.
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Check for leaks
Watch it for a minute, then look again an hour later.
Coming back to a system after more than two weeks off, flush it for a couple of minutes first. After six months standing, replace the cartridges rather than trusting them.
Changing your UV lamp and quartz sleeve
Watch it done
Both are an annual job, at the same service. The sleeve scales up and clouds over, and a cloudy sleeve blocks the UV before it ever reaches the water.
The Hybrid maintenance kits include a new quartz sleeve, so the simple answer is to fit the new one every service and not think about it. If you are replacing a lamp on its own, clean the old sleeve with SC1000 sleeve and scale cleaner and put it back if it comes up clear.
On bore water around here they scale up fast, which is the main reason the kit includes one.
Never touch the glass
Skin oils on a lamp or a quartz sleeve burn on and block ultraviolet. Handle both with a clean lint free cloth. If you do mark one, clean it with an alcohol based cleaner before it goes back in.
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Kill the power and let it cool
Unplug the controller. Give it a few minutes. The lamp runs hot.
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Release the lamp connector
Ease the connector off the top of the lamp. Do not pull on the wires.
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Withdraw the lamp
Straight up and out, slowly, holding it by the ceramic end. It is glass, inside a glass sleeve.
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Doing the sleeve as well? Drain the chamber first
Turn the water off and relieve the pressure as before. Undo the sealing nut at the bottom of the chamber. Water will come out and the spring behind the nut will drop, so have a hand under it and the bucket below.
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Fit the new sleeve, or clean the old one
If your kit came with a sleeve, fit it and bin the old one. If you are reusing, soak the scale off with SC1000 sleeve and scale cleaner and rinse it well. It is made for quartz, unlike household descalers, and it will not scratch the sleeve the way a scourer does. If it stays cloudy, is scratched, or is chipped at either end, replace it. A marginal sleeve is not worth the callout.
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Fit new o-rings
Every time the chamber is opened. They flatten and harden with age, and a reused one is the usual reason a chamber weeps afterwards. The maintenance kits include them.
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New lamp in, reconnect, reset the timer
Lamp in, connector on, power up. On an E Series controller, press and hold the silver button for about 15 seconds until it beeps, which resets the lamp counter to 365 days. Skip this and the alarm will not tell you the truth next year.
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Water back on, flush and check
Flush for three to five minutes. Check for leaks, then check again after an hour.
Leave the UV powered on all the time. Switching a lamp on and off shortens its life far more than running it does.
Getting the right lamp
This is the one we get wrong calls about more than anything else. The lamps look nearly identical and only one of them fits. Check your system model before you order.
| Your system | Lamp | Quartz sleeve |
|---|---|---|
| Hybrid G, R and P series, and WU-UV | RL6 | RQS6 |
| Hybrid E and I series | RL7 | No separate sleeve is sold here, it comes in the maintenance kit |
| Hybrid H series | RL5 | RQS5 |
Fitment never carries across series. An RL6 will not do the job of an RL7 no matter how similar they look. We do not stock the H series parts, so if you have one, ring us and we will get them in.
Not a Puretec system?
The job is the same on any UV steriliser: annual lamp, clean or replace the sleeve, fresh o-rings, never touch the glass. We carry replacement lamps for most of the other brands installed around here, so you do not have to go back to whoever fitted it.
| Your system | Lamp |
|---|---|
| Davey UV50 or UV70 | RL550D |
| Davey UV130 | RL840D |
| Davey UV40-20, UV75-25, Bronze or Silver | RL4 |
| Waterguard Gold, or Wyckomar UV-1200 | RL4-75 |
| Wyckomar UV-250 | RL3 |
| Greenway GAUV-15 or GAUV-15V | RL2 |
| Greenway GAUV-10S | RL550 |
| Cuno S36RL | RL36S |
Replace every 12 months regardless of brand. A lamp that still glows is not proof the water is being treated. While the chamber is open, check the sleeve and fit a new chamber o-ring.
Cannot find your model? Photograph the label on the unit and email it through. We will identify the lamp and tell you honestly if we cannot get it.
Not sure which system you have
The model is on the label on the front of the unit. Photograph it and email it through, and we will tell you what it takes.
Buy the kit, not the parts
The annual maintenance kit holds the right cartridges, the right lamp, the sleeve and the o-rings for your model, under one part number. It removes the guesswork and it lands cheaper than the pieces separately.
Need a hand, or want us to do it?
We service filtration and UV around Waihi, Thames and the Coromandel every week. If you would rather not do it yourself, or the sleeve will not come clean, book us in. A real person picks up.
