A mechanical head, model T5019W0, M30 x 1.5 to EN 215, with a zero position that closes fully. EUR 11.99, rated 4.5 from 1,179 reviews. The maker claims up to 6% off heating. That price holds only on an M30 body; M34 needs an 11.62 adapter.

What you need to know

In a Dutch rental, the knob on the radiator is often the oldest part in the flat: the numbers worn off, no heat at the top of the range, or no way to shut it properly. The Honeywell Home Thera-5 thermostatic head is the cheapest way to replace one, at EUR 11.99, rated 4.5 from 1,179 reviews, dispatched and sold by Amazon and carrying Amazon's Choice in its category. The model is T5019W0: a mechanical knob, 50 mm across and 78 mm long when open, with an M30 x 1.5 connection to EN 215. It has a zero position, which means it can genuinely close, letting that radiator go cold instead of idling on a low setting.

The manufacturer prints one line on its own listing that you can calculate with directly: save up to 6% on heating costs. That is where the sum starts. Take last winter's gas bill, multiply by 0.06, and that is the most this knob can save you in a year; divide EUR 11.99 by that figure and you have its payback in years. A whole flat usually has more than one radiator, so what you actually spend is EUR 11.99 times the number of radiators you own.

Model T5019W0, mechanical knob, M30 x 1.5 connection to EN 215, with a zero position that closes fully. (source 1)
EUR 11.99 including VAT, rated 4.5 from 1,179 reviews, dispatched and sold by Amazon, returnable within 30 days. (source 1)
Manufacturer's figures: about 28 degrees between positions 0 and 1, ambient maximum 40 degrees; fit at roughly 10 Nm, preferably horizontally. (source 1)
If your valve body is M34 x 1.5 rather than M30, you also need an adapter, and the one listed as frequently bought together costs EUR 11.62. (source 1)

The second sum is where this goes wrong most often. EUR 11.99 is the whole cost only if your valve body is already M30 x 1.5. Plenty of older Dutch radiators are not, and with the EUR 11.62 adapter the total becomes EUR 23.61, close to double, at which point better-rated complete sets sit in the same price band. So do one thing before ordering: unscrew the old knob and measure whether the male thread on the valve body is 30 mm. That step is free, and it decides whether this is a 12-euro job or a 24-euro one.

It is also worth saying what this is not. It is a purely mechanical knob with no timer, no app and no remote control. The specification table on the listing carries a line reading Wi-Fi, which contradicts the mechanical-knob line directly above it; go by the control type. Anyone who wants the heating to drop automatically overnight needs a programmable head instead, and in the same set of results the Eurotronic Comet Plus is EUR 17.13, rated 4.0 from 3.2 thousand reviews, EUR 5.14 more. Renters should check one more thing: you are replacing the head, not the valve body, so the landlord's pipework is untouched, but a clause in your contract about not altering heating equipment still governs.

Price: EUR 11.99 including VAT (Amazon.nl, checked 9 September 2026)
Rating: 4.5 from 1,179 reviews, Amazon's Choice
Specs: Honeywell Home Thera-5, model T5019W0, mechanical knob, M30 x 1.5, EN 215, 50 mm across and 78 mm long, zero position
Platform: Amazon.nl, sold and dispatched by Amazon, returnable within 30 days
Checked: Price, rating, review count and every specification read from the listing on 9 September 2026

Hokimi field note: measure the thread before you choose a head. This article contains an affiliate link; ordering through it costs you nothing extra.

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