FAQ
TL;DR: Upgrading a 120 L Galmet (2004) tank with a 2 kW electric flange-type heater raises hot-water availability while adding ≈25 % to energy cost; “always fit a 6 bar safety group”[Elektroda, DiZMar, post #17185317] Why it matters: correct retrofits stop leaks, shocks and enamel failure.
Quick Facts
• Typical 2 kW heater warms 120 L from 15 °C to 45 °C in ~2 h, using ≈2.5 kWh[DOE, 2021]
• Galmet OEM metal flange Ø125 mm with 5/4" thread costs ~€15–20 plus gasket[Galmet Shop, 2023]
• Safety valve for DHW must open at 6 bar per EN 12897[EN 12897]
• Annual anode check adds <€10 but can double tank life[EST, 2020]
• Flow-through heater needs ≥3×16 A breakers; storage heater needs one 10 A breaker[Elektroda, 1 PAWEL, #17185302]
Can I fit an electric heater to a 2004 Galmet 120 L boiler?
Yes. Cut access foam, unbolt the inspection lid, and swap it for a Ø125 mm metal flange with a 5/4" threaded socket, then screw in a thermostat-equipped immersion heater[Elektroda, Michelson, post #17190316]
Threaded or flange-mounted heater: which type fits?
Most Galmet tanks lack an internal 5/4" boss, so choose a flange plate with threaded muffle; a plain screw-in element will not seal[Elektroda, DiZMar, post #17189084]
What power rating heats 120 L fastest without overloading wiring?
A 2 kW element draws 8.7 A on 230 V, safe on a 10 A circuit. It lifts water 30 °C in about 2 h. A 3 kW unit halves the time but needs a dedicated 16 A breaker[DOE, 2021].
Will my electricity bills explode?
Heating 120 L daily with a 2 kW element adds roughly 75 kWh/month—≈€20 at €0.27/kWh—about 25 % more than coal or gas coil heating[EST, 2020].
Is adding an instantaneous (flow-through) heater cheaper to run?
Flow units avoid standing-losses, so they save 5-10 % energy, but require higher peak power (6–12 kW) and thicker cables[Elektroda, 1 PAWEL, #17185302].
How do I relocate the magnesium anode after installing the heater?
Drill the lid, weld or braze an M8 stainless socket, screw the new anode so it touches tank metal; loose rods give no protection[Elektroda, dabu, post #17205937]
What happens if I weld a muffle directly into the tank wall?
Arc heat destroys the internal enamel locally, exposing steel; leaks may appear within a year—an edge-case many DIYers regret[Michelson, #18183466].
Do I need to drain the tank before fitting the element?
Yes. Shut water, open a hot tap, remove the lid, and fully drain to avoid spills and let sediment flush[Elektroda, Anonymous, post #17189138]
Three-step how-to for safe retrofit?
- Drain and remove inspection lid. 2. Bolt on flange with heat-resistant gasket, thread in heater plus thermostat. 3. Add 6 bar safety group and 8–12 L expansion vessel, then fill and test for leaks.
Why is my safety valve dripping after conversion?
Thermal expansion raises pressure to >6 bar; without an expansion vessel the valve weeps. Fit a 6 bar safety group and 8 L vessel, then limit supply to 3 bar via a reducer[Elektroda, W0jtek92, post #17256296]
Can I use a central-heating safety group on domestic hot water?
Yes, if it’s rated 6 bar and uses stainless internals; just note its 0–3 bar gauge will wrap past scale[Elektroda, W0jtek92, post #17256258]
How often should I check or replace the anode?
Inspect annually; replace when over 50 % consumed. Hard or aggressive water can dissolve it in 2 years[Elektroda, Michelson, post #17191511]
