I’m the office administrator for a 180-person company with two sites in London and one outside Boston. I manage the facilities budget — about £60,000 a year across 15 vendors — so I place the orders for everything from boiler servicing to leaf blowers. This checklist came from five years of learning what to ask before I sign a quote.

Use it if you’re in the same situation: you need a Vaillant boiler serviced, you’re not sure whether to repair or replace it, and the grounds team wants new equipment. It’s a procurement checklist, not a DIY guide. Six steps.

Step 1: Book the Vaillant Boiler Service Before You Need It

Routine servicing is the least exciting order I place, but it saves the most money. When I search "Vaillant boiler servicing near me," I’m not looking for the first result — I’m looking for an engineer who can prove they’re Gas Safe registered and actually knows Vaillant boilers.

A decent annual service quote should cover the standard checks clearly. If it doesn’t list what’s included, ask. Then ask the deeper question:

"What’s not included?"

Some quotes treat a magnetic filter flush as an extra. Others include it. Some include replacing the pressure relief valve; others bill it separately. There’s no right answer, but the price should be clear before work starts.

Whenever someone does gas work at our London sites, I verify their Gas Safe number before they arrive. Anyone touching a gas boiler needs to be on the Gas Safe Register. If they hesitate, I move on.

Step 2: Treat "Vaillant Boiler Repairs London" Like a Mini Audit

When a Vaillant boiler breaks down, I search "Vaillant boiler repairs London" and get three quotes. But I compare the scope first, price second. A £240 quote and a £390 quote can be the same job — the cheap one might just exclude the part that fails six months later.

My biggest regret from 2021: I accepted a verbal quote from an engineer who said “we’ll sort it.” He replaced the diverter valve but didn’t test the heating mode. I only found out when the radiators stayed cold. If I’d asked for a written scope, I’d have had a clear case for the follow-up visit. Instead, I paid £540 for a "repair" that didn’t fix it (ugh, again).

Now, any repair quote needs answers to:

  • Are you using Vaillant OEM parts?
  • Is there a parts-and-labour warranty on the repair?
  • Does the quote include a flush if needed?
  • What’s the call-out fee, and is it credited if I use you for the repair?

That last one is a transparency test. If the fee is hidden or non-creditable, it tells me the pricing won’t be any clearer later.

Step 3: Run the Repair-or-Replace Numbers

At some point, a repair quote becomes a replacement quote disguised. I use a simple rule of thumb: if the boiler is over 10 years old and the repair is over half the installed cost of a new one, I start looking at replacement.

For example, we spent £850 in one winter on a 12-year-old Vaillant combi. A replacement quote was £2,300 installed, with warranty and commissioning. That was the moment I stopped approving individual fixes.

This is also where the heat pump vs furnace question shows up. For our US site, which has ducted forced-air heating, it makes sense to compare a heat pump with a gas furnace. For our London sites, with radiators, the comparison is heat pump vs gas boiler. Different systems, same rule: get the full cost picture, not the price of one box.

Step 4: Compare Heat Pump vs Furnace on 10-Year Costs, Not Sticker Price

A heat pump quote can look too high at first. But transparent pricing matters even more here because the long-term costs depend on install quality and ongoing electricity tariffs.

Ask your installer for a 10-year estimate that includes:

  • Seasonal efficiency and expected running cost
  • Maintenance and annual service cost
  • Hot water cylinder or buffer tank (if needed)
  • Electrical upgrades, such as a new consumer unit
  • The cost to remove the old boiler or furnace

In the UK, make sure the installer is MCS-certified if you want the Boiler Upgrade Scheme grant — as of January 2025, that’s £7,500 off an air-source heat pump. Not all quotes include the grant, and some quotes silently add fees for system design or insulation top-ups. That’s the kind of hidden cost that turns a "good price" into an expense report shock.

Even after choosing the new heat pump installer, I kept second-guessing: what if the quoted efficiency was too optimistic? The four weeks until commissioning were stressful. When the monitoring data matched their estimate, I finally relaxed. Ask for the data, not just the brochure.

Step 5: Buy the Right Backpack Leaf Blower, Not Just the Loudest One

For the US site, the grounds crew asked for a backpack leaf blower. They weren’t tied to a brand, but our maintenance contractor recommended Milwaukee. When I searched "Milwaukee leaf blower," I found two options: handheld and backpack. For clearing parking lots and walkways, the M18 Fuel backpack model made sense.

But the biggest difference in quotes wasn’t the blower itself. It was batteries and chargers.

A quote that looks cheaper might come with no battery or with the older charger. When you add two 8.0Ah batteries and a rapid charger, the total jumps. If you already own Milwaukee M18 tools, buy the bare tool and save the cost. If not, include batteries in the honest comparison.

The surprise wasn’t the price difference. It was the local dealer who included a five-year warranty and a loaner battery while ours was being serviced. That’s the kind of cost that never appears on a compare page, but it’s real value.

Step 6: Verify the Paperwork Before You Place the Order

This is the step I care about as the person who gets blamed when finance rejects an invoice. Before I buy anything above £500, I ask for a sample invoice. If the supplier can’t show a proper VAT invoice with item lines, I don’t order.

I still kick myself for not doing this with a maintenance supplier in 2023. They gave me a handwritten receipt for a £2,800 boiler repair job. Finance rejected it, and I had to chase a formal invoice for a month. The lesson: check the paperwork before you pay, not after.

Payment terms are part of the quote too. Net-30 might sound fine, but if the vendor wants full payment upfront, that changes cash flow. Ask for it in writing.

The Mistakes I Still Watch For

Not every supplier problem comes from bad intentions. It comes from assumptions. A few things I check on every order:

  • Old boiler disposal fees — one quote added £120 for collection. Ask whether removal is included.
  • Boiler service history — keep the records. Vaillant’s warranty often depends on a proper service history.
  • Battery compatibility — a Milwaukee leaf blower may share M18 batteries with other tools, but only if you buy the right package.
  • Heat pump grant paperwork — the MCS certificate has to be issued before the installer submits the grant claim. It’s not automatic.

The point of this checklist is to make the hidden details visible before you commit. If a supplier doesn’t want to answer "what’s not included," that’s the biggest red flag of all.