Tankless Water Heater Installation Proposal Template
Turnkey proposal scope for replacing traditional 40-50 gallon tank water heaters with high-efficiency condensing gas or electric tankless systems.
Complete Scope of Work
Copy or customize these verbatim specifications into your contractor proposal.
1. Old Tank Removal & Environmental Disposal
Draining and removal of existing tank water heater.
- Shut off domestic cold water main and natural gas supply lines.
- Drain 40–50 gallon storage tank and remove calcium sediment.
- Disconnect flue, water lines, and fuel gas piping; dispose of old tank legally.
2. Gas Line Sizing & Piping Upgrade
Natural gas supply verification and upsizing.
- Perform fuel gas pipe demand calculation (tankless requires 160k–199k BTU vs. 40k BTU on tank).
- Install new 3/4-inch or 1-inch black iron gas line connection with full-port manual shutoff valve and sediment trap (drip leg).
- Perform 15-minute gas pressure test using digital manometer to confirm zero line loss.
3. Tankless Mounting & Dedicated Venting
Mounting unit, dual-pipe PVC venting, and water hookup.
- Mount condensing tankless water heater securely to interior wall or exterior rated enclosure.
- Install dual-pipe PVC/polypropylene direct exhaust and intake combustion air venting through exterior wall or roof.
- Install full-port isolation service valve kit with integrated hose drain bibs for future annual descaling maintenance.
- Install thermal expansion tank and lead-free pressure relief valve piped to within 6 inches of floor.
4. Water Filtration, Commissioning & Warranty
Scale protection, testing, and warranties.
- Install scale-prevention cartridge filter system to protect copper/stainless heat exchanger from mineral calcification.
- Commission digital controller: set domestic hot water temperature to standard 120°F.
- 15-Year manufacturer heat exchanger warranty, 5-year parts warranty, and 2-year contractor labor warranty.
Standard Line-Item Material Allowances
Clear material specifications that protect against ambiguous scope arguments.
| Component / Assembly | Standard Specification | Unit / Allowance |
|---|---|---|
| Condensing Gas Tankless Heater | 199,000 BTU 9.5+ GPM 0.95 UEF high-efficiency | 1 Unit |
| Webstone Isolation Valve Kit | Lead-free brass with integrated 3/4-inch hose drain ports | 1 Set |
| PVC / Polypropylene Direct Vent | 2-Inch or 3-Inch Schedule 40 venting with terminations | Kit |
| Thermal Expansion Tank | 2-Gallon potable water rated expansion tank | 1 Unit |
| Anti-Scale Filtration System | Polyphosphate or catalytic anti-scale water treatment cartridge | 1 Unit |
Scope-Gap Protections: 3 Clauses to Include
These contractual gotchas account for 85% of change-order arguments on tankless water heater installation proposal templates.
The Risk: Old tank water heaters run on 1/2-inch pipe (40,000 BTU); tankless units require 199,000 BTU (often requiring 3/4-inch or dedicated line back to meter).
Protective Clause: Explicitly states whether a dedicated gas line run from the main meter is included or quoted as an addendum.
The Risk: Condensing tankless units produce acidic condensation (pH 3–5) that dissolves cast iron and copper drains.
Protective Clause: Specifies installation of an inline limestone condensate neutralizer kit before drainage into domestic wastewater.
The Risk: Water hardness exceeding 7 grains per gallon scales up heat exchangers within 24 months, voiding factory warranties.
Protective Clause: Requires installation of anti-scale water filter or pre-existing water softener verification.
Governing Building Codes & Standards
Frequently Asked Questions
Why do tankless water heaters require larger gas lines than traditional tank heaters?▾
A traditional tank heats 40 gallons slowly over an hour using 40,000 BTU. A tankless unit heats water instantly on demand as it flows through, requiring up to 199,000 BTU of natural gas capacity.
What is an isolation valve kit and why is it necessary on tankless units?▾
Isolation valves allow a plumber to isolate the water heater from the home and circulate vinegar or descaling solution through the internal heat exchanger without disconnecting household plumbing.
Related Plumbing Proposal Scopes
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