Combi boiler service in Kocaeli and İzmit
Boiler broken down? We'll come to you.
We come to your home anywhere in Kocaeli for boiler servicing, boiler repair, radiator cleaning and installation. We find the fault on site and tell you the price before we start.
What do you need help with?
- Boiler repairWon't ignite, no heating, error code
- Boiler serviceAnnual service, before winter
- Radiator cleaningRadiators not heating, cold at the bottom
- Boiler installationNew boiler, moving a boiler
İlhan speaks only Turkish. Write to us in English on WhatsApp: he reads your message and replies with a translation app.
- On-site diagnosis
- Price agreed first
- 1-year workmanship guarantee
Weekdays 08:00–20:00Saturday 09:00–18:00
SundaysFor emergencies, you can still contact us
All of KocaeliWe come to your home and check on site
Why Dereli Teknik?
Two things frustrate customers most: the technician not turning up, and the price going up afterwards. We do neither.
Workmanship guarantee
If the same fault comes back within a year, we don't charge.
On-site diagnosis
We find the fault at your home and tell you what needs doing and the price before we start.
Book online
See the available days and times and choose the one that suits you. The time you choose is not given to anyone else.
Pressure keeps dropping?
When the boiler is cold, the gauge should read between 1 and 1.5 bar. If you keep having to add water, there is a leak somewhere.
We cover all of Kocaeli
From İzmit to Gebze, from Kandıra to Karamürsel: we come to your home and check your boiler on site.
We show you the replaced part
We show you the old part we removed. We don't replace parts that don't need replacing.
We arrive when we say
If we are running late, we let you know in advance.
We work cleanly
We protect the floor and leave the work area tidy when we finish.
All combi boiler brands
We are an independent service; we choose the right part together with you.
Services
We handle servicing, repair and installation of gas combi boilers, all from a single service.
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Boiler service
Annual service: burner and heat exchanger cleaning, gas and water leak checks, pressure adjustment, testing of the safety parts.
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Boiler repair
Boilers that won't ignite, don't heat, keep locking out, lose water pressure or show an error code.
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Boiler installation
New boiler installation, moving a boiler, and flue and pipe connections made in line with regulations.
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Radiator cleaning
Machine cleaning and a system check for radiators that don't heat up or stay partly cold.
Examples of our work
A few photos from the field and a short video.
On-site fault finding on a boiler showing an error code 
The front cover comes off and each internal part is checked 
Checking the gas valve and cable connections 
Checking the electronic board
Inside a boiler that has missed its services
In the video you can see dirt, rust and soot built up on the floor of the combustion chamber and around the burner. This build-up lowers the boiler's efficiency, increases gas use and leads to faults over time.
In the annual service this area is cleaned, and the settings and safety parts are checked. The best time is before winter.
Book a service on WhatsAppWhat our customers say
- Ömer★★★★★
Hızlı ve kusursuz bir işçilik . Geç saatte başıma gelen arızaya saat farketmeksizin yetişen mükemmel bir usta samimi ve iyi yaklaşımlarıyla hem müşteri hizmeti hem iş hizmeti olarak 10/10 . Çok memnun kaldık Dereli teknik 💯
- İbrahim Kaplan★★★★★
Temiz ve güvenilir bir şekilde sorunumuz çözüldü.
Benim tahmin ettiğim fiyatın çok altında kalan bir hizmet oldu.
Cumartesi akşam olmasına rağmen aramam ile sorunun çözülmesi iki saati bulmadı.
Teşekkürü bir borç bilirim.
How we work
Four steps from your first message to a working boiler.
- Get in touchOn WhatsApp, in English. We ask for your boiler's brand and the problem.
- AppointmentWe agree on a day and time slot that suits you.
- On-site diagnosisWe find the fault, tell you the price and get your approval.
- Repair and handoverWe finish the job, test the boiler and explain what we did.
About us
Dereli Teknik is the combi boiler service that İlhan Dereli has run in Kocaeli and İzmit since 2019.
We are not a dealer for any brand; we work independently. That is why we work on all combi boiler brands and suggest the solution that suits you best. We approach every job the same way: we find the fault on site, explain what needs doing and the price before we start, and never begin without your approval. We show you the part we replaced and give a one-year guarantee on our workmanship.
Our aim is not to come once and be gone, but to be the service that looks after your boiler every year and that you can reach whenever you need us.
Where we work
We come to your home anywhere in Kocaeli. If your district is not on the list, message us and we'll see what we can do, depending on the distance.
- İzmit
- Gebze
- Darıca
- Çayırova
- Dilovası
- Körfez
- Derince
- Gölcük
- Başiskele
- Kartepe
- Karamürsel
- Kandıra
Frequently asked questions
If your question is not here, message us on WhatsApp.
How often should a combi boiler be serviced?
Once a year, ideally before winter. Regular servicing lowers gas use and makes a breakdown in the middle of winter less likely.
How long does a service take?
A standard boiler service takes about 45–60 minutes. For repairs, the time depends on whether a part needs replacing.
Which boilers do you work on?
We work on all gas combi boilers. We are an independent service; when choosing parts, we show you options that are suitable and of good quality, and we decide together.
Can I find out the price in advance?
For a service, we give you a clear price in advance on WhatsApp. For a fault, the price is given after the on-site diagnosis, and we never start work without your approval.
Do you work at weekends?
We are open on Saturdays from 09:00 to 18:00. On Sundays you can contact us for emergencies.
Boiler guide
What you can safely do at home while you wait for a technician, and how to use your boiler more efficiently.
- Why does combi boiler pressure drop, and what should you do?
What should the pressure be, why does it drop and how do you add water?
- Why are your radiators not heating up?
Cold at the top, cold at the bottom or not heating at all: causes and fixes.
- Error code on your combi boiler display: what it means and what to do
What the codes indicate, when a reset helps and when to get help.
Message us on WhatsApp
Just tell us your boiler's brand and the problem. İlhan speaks only Turkish: write in English and he replies using a translation app. From a photo of the display or the error code we can often tell roughly what the fault is.
Phone (Turkish only): +90 535 255 88 00
Your contactİlhan Dereli (speaks Turkish)
Working hoursWeekdays 08:00–20:00
Saturday 09:00–18:00AreaAll of Kocaeli, at your home