Combi vs System vs Regular Boiler (London) | Costs, Pros & What Fits Your Home | ARA Services

Combi vs System vs Regular Boiler (London)
pick the right type first — then talk price

This is the exact conversation we have on the phone most weeks. Someone’s boiler’s on its last legs, they’ve got ten tabs open, and the question underneath it all is: “What actually suits my place — and am I about to buy the wrong thing?”

We’re ARA Services Ltd — Gas Safe engineers based in Forest Gate (E7). We’re around Romford Road / Woodgrange Road a lot, and we bounce across North & East London most days. If you want a straight recommendation, call +44 7727 154 746. No finance plans, no scripts — phone first.

Worcester • Vaillant • Ideal Flats • houses • conversions North & East London
Updated: 22 Dec 2025 • Written by working engineers (not a brochure)

TL;DR (the quick answer people actually want)

If you only read one section, read this. Boiler type is mainly about how you use hot water, not what’s “best on paper”. Pricing comes after the right choice. If you want a full install overview, here’s our boiler installation process (done properly).

Choose a combi if…

You’ve got sensible hot water demand (often 1 bathroom), decent water pressure, and you want to ditch cylinders/tanks.

Choose a system boiler if…

You’ve got higher hot water demand (two bathrooms, busy mornings) and you want that steady “cylinder calm”.

  • Usually quieter day-to-day in family homes.
  • Plays nicely with multiple showers one after another.
  • Costs depend on cylinder condition, controls, pipework, and access.

Choose a regular boiler if…

You’ve already got tanks/cylinder and the setup genuinely suits the property — especially some older houses with specific layouts.

  • Sometimes it’s the right call, sometimes it’s just “what’s always been there”.
  • Good choice when pressure is tricky and storage makes sense.
  • If you’re debating change costs, see: boiler change price examples in London.

Want the numbers as well as the decision? Here’s the clean cost page: full new boiler cost breakdown.

Our “kitchen-table” method for choosing the right boiler

We don’t start with “Worcester or Vaillant?” We start with the boring stuff that decides whether you’ll love the boiler or hate it: how many bathrooms, what your mornings look like, whether the kitchen tap turns sad when the heating kicks in, and what the pressure feels like on a normal weekday.

Little London detail: we’ve been in plenty of places where the owner says “it’s fine” — then you turn the tap and it’s basically a polite drizzle. That’s how people end up with the wrong combi on paper.

If you’re also choosing brand, we’ve written it up properly here: Worcester vs Vaillant vs Ideal (honest comparison). But type first. Brand second.

What usually decides it (in real London properties)

Here’s what we check before we recommend combi/system/regular. Not theoretical. This is the stuff that changes the job and the comfort. If you’re comparing properties (flat vs terrace vs conversion), this is worth a look too: how property type changes the quote.

Hot water demand

One bathroom and normal use? A combi can be perfect. Two bathrooms with back-to-back showers? System boilers start looking attractive fast.

Water pressure reality

Combi performance depends on incoming mains pressure/flow. If it’s weak, you’ll feel it every day — especially in top-floor flats.

Space and layout

Flats often want to lose cylinders for space. Houses sometimes keep a cylinder because it just works for busy households.

Existing system condition

If the system is tired (sludge, uneven rads), we plan cleaning/protection properly. It’s not an “extra”, it’s keeping the new boiler alive.

Three tiny examples we see all the time

1) Forest Gate conversion flat: one bathroom, decent pressure, boiler in a kitchen cupboard. Combi made sense. The win wasn’t the brand — it was sizing it properly and setting it up so it didn’t short-cycle all day.

2) Family house with busy mornings: two bathrooms, “everyone showers at once” energy. System boiler + cylinder kept things calm. Nobody wants to be the person who turned the tap and stole the hot water from upstairs.

3) Older regular setup: customer wanted a combi because it sounded modern. Once we looked at the pressure reality + layout, keeping a stored hot water setup was the better day-to-day experience. If you’re stuck on “repair vs replace” right now, this helps: repair vs replace — what usually wins long-term.

Want us to pick the right type for your home?

Call +44 7727 154 746 and tell us: bathrooms, boiler location, and whether you’ve got a cylinder. If you’re stuck near Forest Gate station with no hot water, say that first — we’ll be straight about timings.

Call — quick recommendation

Prefer messages? send photos for a quick recommendation (boiler + controls + any cylinder/tank + a shot of the flue exit area).

Cost reality (without turning this into a spreadsheet)

Boiler type affects installed cost mainly because it changes what else is involved: cylinder work, pipework changes, controls, space, and time. If you’re specifically researching “fitted” pricing, start here: what ‘boiler fitted cost’ actually includes.

System / regular installed costs

You’re dealing with stored hot water components. If the cylinder/valves/controls are tired, the job gets bigger — but it often performs better for busy homes.

For broader ranges: full new boiler cost breakdown.

What people mention after we’ve finished

You’ll notice a pattern in reviews: it’s not “they sold me X brand”. It’s “they were professional, quick, tidy, and explained it”. That’s what matters in real houses.

“My boiler went wrong… Abdul and his team came and fitted a new one. They worked without taking a break, cleaned up when…”

Alison Louis

“Brilliant Service! Identified the issues immediately and fixed the problem. Very professional.”

Rachel Boston

“Great service prompt and efficient… fitted a new boiler at a very competitive price… took away old boiler and all other waste.”

Grant Hodges (Local Guide)

FAQs (real questions, real answers)

Is a combi always cheaper to install?

Not always. A like-for-like combi swap can be straightforward, but conversions and relocations can add time and parts. The cheapest option is usually the one that suits the property without forcing awkward changes.

We’ve got two bathrooms — does that automatically mean “system boiler”?

Not automatic, but it’s a strong hint. Two bathrooms often means you’ll appreciate stored hot water. We’ll still check pressure and usage patterns — some homes are two-bathroom on paper but used like a one-bathroom home.

Can I switch from a regular boiler to a combi?

Often yes, but we only recommend it when it improves the day-to-day experience. If your pressure isn’t great, a combi can feel like a downgrade even if it’s newer. If you want examples of change pricing, see boiler change price examples in London.

Which brands do you fit for these boiler types?

We regularly install Worcester, Vaillant and Ideal across combi/system/regular setups. Brand matters, but “matched to the home + installed properly” matters more. If you’re stuck between brands: our comparison is here.

How do I get a recommendation without a home visit?

Call +44 7727 154 746 or send photos via the contact form. Photos of the boiler area, controls, and cylinder/tanks (if you have them) get us 80% of the way quickly.

Want the right boiler type for your home — not a generic answer?

Give us the basics (bathrooms, pressure feel, boiler location) and we’ll tell you what fits: combi, system, or regular. Then we’ll talk price properly. Phone first: +44 7727 154 746.

Call ARA Services now