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About us

We manufacture the Fit Once™ cartridge which is compatible with Vaillant, Glow-Worm & Heatline combi-boilers. Click Learn More below to see our video & find out more.
We are the UK Number One serviceable cartridge manufacturer for this boiler range.
Fit Once™ is designed patented and manufactured in the UK with quality materials and this is all we sell so you know you are buying a product with 100% positive feedback.
Unlike other cartridges, Fit Once™ is serviceable and due to the patented design there is no need to drain the boiler to change the seals.
Comes with a 12 month manufacturers warranty. Buy the best, buy Fit Once™.
Location: United KingdomMember since: 20 Nov, 2011Seller: buycombi

Business details

Business name: Buycombi LtdAddress: Heatherview, Sl98nj Gerrards Cross, United KingdomEmail:

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Detailed seller ratings

Average for the last 12 months

Accurate description
Reasonable postage cost
Delivery time

Seller Feedback (847)

l***i (248)- Feedback left by buyer.
More than a year ago
Verified purchase
Fast delivery and arrived a day early. Item was as described and the tools provided came in handy especially with the YouTube video. One helpful tip from another video was to ensure you instal the valve with the slot in the right place or else you won’t have heating. Overall good package and would use again. Other products are available cheaper. Inclined to use those next time since I have the kit now. Saved me over £100 in call out charges etc. Cheers and GOD BLESS
Reply from: buycombi- Feedback replied to by seller buycombi.- Feedback replied to by seller buycombi.
Hi, thanks for the positive review. Just to clarify, there are no other cheaper serviceable cartridges available. Our Fit Once cartridge enables you to change the worn seals without draining the boiler so the cartridge is installed permanently. This is a unique design that we make in the UK. Cheers.
v***j (340)- Feedback left by buyer.
Past 6 months
Verified purchase
As described, did the job, quick service, thank you
e***d (684)- Feedback left by buyer.
Past 6 months
Verified purchase
Cartridge as described and rapid delivery
h***s (505)- Feedback left by buyer.
Past 6 months
Verified purchase
As described, perfect hopefully no more replacement other than a washer.. top rated seller keep up the good work.
a***r (1167)- Feedback left by buyer.
Past month
Verified purchase
Smart little device and delivered on time, thank you.
1***1 (1167)- Feedback left by buyer.
Past 6 months
Verified purchase
Great service thanks