Baxi 830 Combi Boiler Review: Is It Any Good?

Is the Baxi 830 a good boiler?

For the house it was designed for, yes. The 830 sits in Baxi's 800 Combi 2 range, the range Baxi puts its longest warranty on, and it arrives with the magnetic filter, the pre-heated condensate trap and OpenTherm control support.

What is genuinely good about it

• A 10-year parts and labour warranty, the longest Baxi offers on any of its boilers.
• An Adey Micro 2 filter supplied in the box, so the sludge protection is not an upsell.
• A pre-heated condensate trap, which Baxi says helps prevent freezing in winter and lowers the risk of a frozen condensate pipe. Frozen condensate is the classic reason a modern combi stops in January.
• Certified OpenTherm control, so a modulating thermostat can hold the boiler down at a low, efficient output instead of switching it on and off.
• Baxi states it works on natural gas or LPG without a conversion kit.

What is honestly less good

• The "830" is the hot water number, not the heating number. Central heating output is 25kW maximum at 80/60°C, so most of what the 830 buys you over the smaller 824 is hot water at the tap.
• Baxi's installation manual caps the maximum capacity of the central heating system at 100 litres. A large, heavily radiatored house can exceed that.
• 12.2 litres a minute is a comfortable one-bathroom flow rate, not a two-bathroom one. The 836 is the model for that.
• The 10-year warranty has four conditions attached, and one of them, keeping the supplied filter fitted and maintained, is easy to lose track of years later.
• Like every combi, it cannot give you more hot water than your cold mains delivers.

Is the Baxi 830 the right size for your home?

The 830 is the middle model of the three Baxi sells in the 800 Combi 2 range: the 824, the 830 and the 836. Baxi's own technical data sets them side by side, and most of the difference is hot water.

Read that table before you choose. Stepping up from the 824 to the 830 buys about five extra kilowatts of heating and two extra litres of hot water a minute at the tap, which is the difference between a fine shower and a good one. Stepping up again to the 836 buys hot water only, because the heating output is the same 25 kW.

Two more figures from the manual matter when you are sizing:

• Maximum capacity of the central heating system: 100 litres. That is a limit on the water in your pipes and radiators, not a bedroom count, and a big old system with heavy steel radiators gets there faster than you would think.
• Minimum working water flow rate: 2.0 l/min, with a dynamic minimum pressure of 0.5 bar. Below that the boiler will not make hot water at all. If your mains is weak, no combi in this range fixes it.

If your home is larger, or you run two bathrooms at once, look at the Baxi 836 or, where space is not the constraint, a Baxi heat only boiler with a cylinder. The Baxi 800 range page compares the whole line-up. Sizing is a heat loss calculation, not a rule of thumb, so let a Gas Safe registered installer do it on site.

How much does a Baxi 830 cost?

There is no single price. Baxi does not publish a consumer price for the 830: it sells through merchants and installers, so the number you pay is set by whoever fits it. What moves that total:

• Whether the boiler stays where the old one was, or moves room.
• The flue route, and whether the existing hole and terminal position still comply.
• Pipework changes, a system flush, and fitting the supplied magnetic filter.
• New controls, especially if you want the OpenTherm or uSense control that makes the boiler run efficiently.
• Access, condensate drainage and making good afterwards.

Get two or three itemised quotes from Gas Safe registered installers, and make each one confirm in writing that the supplied filter is being fitted, the Benchmark checklist is being completed and the warranty is being registered. Those three lines are worth more than a small discount, because without them the 10-year warranty is not 10 years. If your current boiler is forcing the decision, our guide on whether to repair or replace a boiler is a better place to start than a price list.

The 10-year warranty, and what quietly cancels it

Baxi gives the 800 range a 10-year parts and labour warranty. It is a real warranty, and it is conditional. Baxi's published conditions are that the boiler is:

• registered within 30 days of installation,
• installed with the Benchmark checklist completed by the installer,
• serviced annually, and,
• on the 800 range only, fitted with the supplied magnetic filter, maintained for the length of the warranty.

Miss the filter condition and Baxi says the warranty "will revert to only two years". Miss the registration, the Benchmark checklist or the annual service and Baxi says it "will revert to the standard one year". Baxi is also explicit that components damaged by sludge and dirt in the system water are not covered, which is exactly why the filter condition exists.

Two practical points. The annual service has to be done by a Gas Safe registered engineer, and you want the filter cleaned at the same visit, with both written on the paperwork. And if you are a landlord, the annual gas safety check is a separate legal duty: the HSE states you must "keep a record of the safety check for 2 years and issue a copy to each existing tenant within 28 days of the check being completed".

Baxi's own warranty information page carries the current terms. Our Baxi warranty guide explains how the registration works and what to do if you have inherited a boiler with no paperwork.

How efficient is the Baxi 830, really?

Baxi rates the 800 Combi 2 at a seasonal space heating energy efficiency of 93%, which is ErP band A, with a water heating efficiency class of A. That is normal for a good modern combi, and it is measured to a standard test rather than to your house.

What decides the efficiency you actually get is how the boiler runs. A condensing boiler only condenses properly when the water coming back from the radiators is cool, so a lower flow temperature and a long, gentle burn beat short, hot bursts. That is why the OpenTherm compatibility is worth using: a modulating control can hold the 830 down near its minimum heating output of 5.8kW instead of firing it flat out and switching it off again. Baxi also states the 800 Combi 2 is compatible with its uSense smart control, so you can operate the boiler from a phone or tablet.

What goes wrong with a Baxi 830?

Most of what stops this boiler is the system around it rather than the appliance. The 830 shows a flashing code preceded by an E when it locks out, and these are the ones from Baxi's manual you are most likely to meet:

Baxi's manual says that for codes including E110, E125, E128, E133, E134 and E135 you can relight the boiler by holding the reset button for one to three seconds, and that if the code keeps coming back, further investigation is required. In plain English: reset it once, and if it returns, book an engineer.

Low pressure is a leak somewhere until proven otherwise, and a boiler topped up more than once or twice a year is losing water for a reason. Our guide to a boiler that keeps losing pressure walks through what an engineer looks for, and the full Baxi fault code list covers the ignition and gas supply codes.

Where to stop. Checking the pressure gauge, checking your gas is on elsewhere in the house, and pressing reset once are homeowner jobs. Opening the case is not. Only a Gas Safe registered engineer may work on the gas side of a boiler. If you smell gas, do not touch the boiler at all: call the National Gas Emergency Service on 0800 111 999 immediately.

Will a Baxi 830 fit where my old boiler is?

Baxi gives the 830 as 700mm high, 395mm wide and 285mm deep, with an installer lift weight across the 800 Combi 2 range of 29.2kg to 30.5kg. Older literature for the same range quotes the width as 390mm, so if you are measuring into a tight cupboard, work off the clearances rather than the millimetre.

The clearances Baxi requires are: 178mm above the casing, at least 150mm below it with 200mm recommended, 450mm in front for servicing and 5mm at each side. That 450mm is the one that catches people out, because a cupboard door and a wall opposite can make a technically legal position an unserviceable one.

Connections are 22mm for gas, heating flow and heating return, 15mm for the cold inlet, hot outlet and pressure relief, and 21.5mm for the condensate. Baxi's manual allows the boiler in a room with a bath or shower in zone 2, but not in zone 0 or 1, and not in any zone if an optional plug-in timer, RF receiver or thermostat is fitted to it.

None of that replaces a site visit. The flue terminal position usually decides whether a swap is straightforward, and only the installer can check that on the wall.

Baxi 830 specifications

Outputs, flow rates, efficiency and dimensions come from Baxi's published data for the current 800 Combi 2 range. The installation detail above, meaning the clearances, connection sizes, system capacity and fault codes, comes from Baxi's 800 Combi Installation and Service Manual, models 825-830-836, which covers the earlier generation of the same range. Baxi has revised this range more than once, so always check the data badge on your own boiler.

Getting a service, a repair, or a new boiler

If something is actually wrong, tell us what the boiler is doing and we will arrange a Gas Safe registered engineer. If you are choosing a boiler instead, we can put you in front of an installer. Either way, ask for a callback and a person will ring you.

Once the Baxi warranty runs out, or if the conditions on it were never met, repairs are yours to pay for per visit. That is the point at which a boiler and central heating cover plan starts to make sense. Smart Plan is a service plan rather than insurance, you pick the modules you want, and once you use a service a 12-month agreement period applies. We work with a national network of thousands of Gas Safe registered engineers. We aim to get an engineer out to you within two working days, and cover plan call-outs are booked Monday to Friday, 08:00 to 18:00. A £95 call-out fee applies in some situations, including during the first 30 days of a plan, when your cover still applies. Boiler and central heating repairs are covered to £500 in a 12-month period if the boiler is under seven years old, or £200 if it is over seven years old.