The Case for Deposits
A boiler installation is one of the most expensive jobs a gas engineer takes on — in both materials cost and time. A typical combi boiler installation ties up £600–£1,500 in the boiler alone, plus fittings, flue, system filter, and possibly a smart thermostat. You may order these materials days before the job, carrying the cost on your account.
Without a deposit, you bear 100% of the financial risk if the customer cancels on short notice, doesn't answer the door, or disappears after completion. A 20–30% deposit on a £2,500 installation is £500–£750 — enough to cover your material outlay if the job falls through, and enough to confirm the customer's genuine commitment.
Deposits also function as a filter. A serious customer who genuinely wants the work done will pay a deposit without hesitation. A customer who balks at a reasonable deposit while happy to accept a £2,500 price is often a warning sign of future payment difficulties.
How Much to Ask For
Industry norms for deposit percentages on gas installation work:
- Standard combi or system boiler swap: 20–30% deposit is universally accepted in the industry. On a £2,000 job, that's £400–£600
- Large installation (full central heating, new build, system upgrade): 30–50% deposit is reasonable. Large jobs involve significant material procurement and multiple engineer days — the risk without a deposit is substantial
- Materials-only jobs: If you're ordering expensive or specialist equipment on the customer's behalf (an unusual boiler, specific smart controls), a materials-only deposit equal to the equipment cost is appropriate
For small service or call-out jobs (under £200), don't bother with a deposit — the friction isn't worth it. Deposits make sense for jobs over £500 where your material outlay and time commitment is meaningful.
When to Ask for Payment in Stages
For larger jobs, consider a three-stage payment structure rather than deposit-plus-final:
- Deposit (20–30%): On acceptance of the quote, before ordering materials
- Progress payment (40–50%): At the end of day one or on completion of first-fix, depending on the job
- Final payment (20–30%): On completion, before handing over certificates and commissioning documentation
This structure is common on larger installations (£3,000+) and commercial work. It means you're never significantly out of pocket at any stage, and the customer never owes you more than a fraction of the total. The final payment on completion creates a natural closing moment: "The job is done, the system is commissioned, here's your benchmark certificate — please make the final payment and I'll hand everything over."
Handling Customer Pushback
Some customers push back on deposits, usually citing one of two reasons: they've been stung by a cowboy trader who took a deposit and never returned, or they simply prefer not to pay until work is done.
For the first concern, address it directly: "I understand the concern — I'll provide you with my Gas Safe registration number, public liability insurance certificate, and a written quote confirming exactly what the deposit covers and the conditions for refund if we cancel." This is a reasonable, professional response that distinguishes you from a cowboy who avoids paper trails.
For the second concern, stand firm but explain: "I have to order your boiler and materials before the installation day — the deposit covers those costs. It's standard practice in the industry and protects both of us." Most reasonable customers accept this explanation. Those who don't were likely going to be difficult payers regardless.
If a customer refuses any deposit on a large job: you have the option to politely decline, or to proceed with payment due on completion — but in the latter case, factor the risk into your decision and consider taking a card reading on site before handing over the documentation.
Make Refund Terms Clear
Include your deposit refund policy in your quote and terms of business. A clear policy prevents disputes:
- Customer cancels 48+ hours before the job: Full deposit refund. You haven't yet incurred specific costs
- Customer cancels with less than 48 hours notice: Deposit retained to cover materials already ordered and the cancelled day rate
- You cancel the job: Full deposit refund, always
The Consumer Rights Act 2015 provides some protection to domestic customers against unfair deposit retention — a retention policy must be proportionate to your actual losses. Don't retain a 30% deposit on a £3,000 job if your actual costs were £200 in materials you can return — that would be disproportionate and potentially challengeable. Retain what reflects your genuine loss.