Heimeier vs Danfoss thermostat
Updated: October 2026
You have a Danfoss body on the radiator and a Heimeier head in the basket, or the other way round, and you want to know which brand is better. Heimeier vs Danfoss thermostat is the wrong question until you name the collar. RA, RAV, and RAVL are different sizes. A standard Heimeier M30 head does not replace all of them, and a Danfoss head is not automatically the better match for a Heimeier insert. The [Heimeier thermostat](/hub/thermostats/heimeier-thermostat) comparison holds the prices. Listings were captured on amazon.co.uk on 15 October 2026. We did not run a lab test. A qualifying purchase through our links can earn a commission at no extra cost to you.
You have a Danfoss body on the radiator and a Heimeier head in the basket, or the other way round, and you want to know which brand is better.
You have a Danfoss body on the radiator and a Heimeier head in the basket, or the other way round, and you want to know which brand is better. Heimeier vs Danfoss thermostat is the wrong question until you name the collar. RA, RAV, and RAVL are different sizes. A standard Heimeier M30 head does not replace all of them, and a Danfoss head is not automatically the better match for a Heimeier insert. The Heimeier thermostat comparison holds the prices. Listings were captured on amazon.co.uk on 15 October 2026. We did not run a lab test. A qualifying purchase through our links can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Connection | Sensor | Scale | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Sanitop-Wingenroth Heimeier K, Danfoss RAVL | Danfoss RAVL | Fixed sensor, liquid-filled | 6–28 °C, marks 1–5 | 9.0 | about £22.75 | View offer |
 Heimeier Heimeier 9712-00.500 for Vaillant | Direct, for Vaillant | Not stated | Not stated | 8.4 | about £29.67 | View offer | |
| Preis-Tipp |  Heimeier Heimeier K-Eco 6071-43.500 | M30×1.5 | Liquid-filled | 16 °C / Eco 20 °C / 24 °C | 5.0 | about £19.00 | View offer |
On this page
There is no single better brand
Compatibility is the criterion, not a winner’s badge. Heimeier makes heads that screw onto its own M30×1.5 inserts, and it also makes direct heads for some other collars, including Danfoss patterns and Vaillant. Danfoss sells a full range of its own liquid-filled domestic heads. Danfoss’s UK overview is a Danfoss catalogue. It does not tell you to fit a Heimeier head, and it is useful here as a reminder that Danfoss is a complete range, not as a score against Heimeier. Response times are easy to misuse. Danfoss quotes bands on its own range: wax is the slowest, liquid is about 15–22 minutes, and gas is about 10 minutes on the commercial line. Heimeier’s K sheet quotes about 19 minutes closing time with an integral sensor. Those are different tests. Do not put them in one race, and do not say Heimeier reacts faster than Danfoss because one number looks smaller. Liquid-filled is what both of the relevant heads in this conversation claim. It is not a brand trophy. The practical split is the collar. If it matches, either brand’s head for that collar can do the job, with the limits of the actual listing you buy. If it does not match, the more expensive head still will not clamp, and an adapter is a different part from a head. An M28×1.5 to M30×1.5 adapter was removed from this comparison because it is not a thermostat.
RA, RAV, and RAVL
Danfoss used three domestic collars, and they are not one size with three names. Danfoss’s own commercial replacement sheet gives RAVL at about 26 mm and RAV at about 34 mm. IMI’s heads overview gives Danfoss RA at about 20 mm, RAV at about 34 mm, and RAVL at about 26 mm. Use those figures together. Bosch’s UK adapter card says RA at 20 or 23 mm and RAVL at 25.5 mm. Treat 25.5 mm as a measuring tolerance next to Danfoss’s 26 mm, not as a fourth product you must hunt for. Older RA bodies are sometimes described at about 20 mm beside a later 23 mm. If you are between 20 and 23 with a tape on a painted collar, you are in the RA family, not in RAVL. Four notches on the collar do not identify the body. A German identifier page warns that RA, RAV, and RAVL can all show four notches. Notches are a clue that you are looking at a Danfoss-pattern valve. They are not a substitute for the diameter or for the letters on the old head. IMI’s direct-head leaflet, with no adapter, lists separate articles: VK 9710-24.500 for Danfoss RA, K 9800-24.500 for RAV, K 9700-24.500 for RAVL, and K 9712-00.500 for Vaillant from 1987. They are liquid-filled, with a 6–28 °C scale. This amazon.co.uk set does not stock the RA or RAV Heimeier articles. It stocks one RAVL-pattern head and the Vaillant article. Only RAVL, among the three Danfoss letters, is present here as a Heimeier direct head.
When the Heimeier RAVL head is the right buy
Buy the Heimeier-style RAVL head when you have measured or read a RAVL collar, about 26 mm on Danfoss’s sheet, and you want a direct head rather than a Danfoss replacement. The listing in this set is about £22.75, liquid-filled, 6–28 °C, marks 1–5, frost protection, and 4.5 from 285 reviews. The seller part is 27135 6. The brand field says Sanitop-Wingenroth, and the item type says a Heimeier thermostatic head K. IMI’s article for a K on Danfoss RAVL is 9700-24.500. Those two numbers are not the same printing. Say both, and do not merge them on the order. Reviewers say it fits a RAVL-style valve without an adapter and is often easier to turn than a stiff Danfoss head. Plastic claw teeth are the complaint that returns, and one unit did not move the radiator. That review file is the reason this head is the top pick on the best Heimeier thermostat head page, and only for this collar. It will not fit an RA click collar. RA is the smaller pattern, about 20 mm, and forcing the about £22.75 head onto it is how the nut fails to start. The Vaillant article 9712-00.500, at about £29.67, is the direct head for Vaillant in this set, not a Danfoss size. One printed UK review says it fitted Vaillant valves. It is the wrong row for RA, RAV, and RAVL alike.
When to stay with Danfoss or use M30
Stay with a Danfoss head when the collar is RA or RAV, because this comparison does not include a Heimeier direct head for those two. Danfoss sells its own heads for its own collars. You may also stay with Danfoss when you want Danfoss’s current domestic head and you are happy to match their connection chart, including where they have moved newer valves to M30. A Danfoss M30 head does exist on amazon.co.uk. A Danfoss Redia M30 listing was in the raw scrape, at £14.99 with 4.2 from 53 reviews, and it was removed from this comparison because the brand is Danfoss, not a Heimeier thermostat. Do not rank it as a Heimeier product. Do not pretend this page tested it against the RAVL head. If the Danfoss body is already M30×1.5, you do not need a special Danfoss-letter head. A normal M30 head fits, including the Heimeier K-Eco 6071-43.500 at about £19.00 in this set. That K-Eco prints M30×1.5 and a short scale. It has no review line. It is still the M30 choice, and the RAVL head is the one to leave in the basket. The recommendation is the collar, not the logo. RAVL, about 26 mm, and the Heimeier-style direct head at about £22.75 is the buy in this shop set. RA or RAV, and you stay with Danfoss or with the matching IMI article this Amazon set does not stock. M30, and you use an M30 head such as the K-Eco, from either brand, once the thread is confirmed. Then fit it by hand, and stop if the nut will not start. The hand method is on how to fit a Heimeier thermostat.
Common questions
Is a Heimeier head better than a Danfoss head?
Neither brand wins as a blanket better head. A Heimeier direct head is the right buy when the collar is one Heimeier actually makes a head for, and when that head is the one in your hand. Danfoss is the right buy when you want Danfoss’s own head for RA or RAV, or a Danfoss M30 head on an M30 body. Liquid-filled response figures from each maker come from different tests, so they are not a league table.
What is the difference between RA, RAV, and RAVL?
They are three collar sizes. Danfoss’s sheet gives RAVL at about 26 mm and RAV at about 34 mm. IMI gives RA at about 20 mm, with the same 34 mm and 26 mm for RAV and RAVL. A UK adapter card’s 25.5 mm for RAVL sits next to 26 mm as a measuring tolerance. RA at 20 or 23 mm is still RA. You measure or read the old head. You do not guess from the shape of the radiator.
Which Heimeier article fits RAVL?
IMI lists K 9700-24.500 for Danfoss RAVL. The amazon.co.uk head in this set is seller part 27135 6, at about £22.75, sold as a Heimeier K with a Danfoss RAVL connection. Use it for RAVL. Do not assume the box will be printed 9700-24.500. The RA article 9710-24.500 and the RAV article 9800-24.500 are not in this shop set.
Will the Amazon RAVL head fit an RA click collar?
No. RA is the smaller collar, about 20 mm, or 20 to 23 mm on the adapter card. The about £22.75 head is the RAVL pattern, about 26 mm. It is the head reviewers describe as fitting Danfoss RAVL-style valves without an adapter. On an RA click collar the nut does not have a matching seat, and tightening it will not create one.
Do four notches mean RAVL?
No. All three patterns can show four notches, so the notches do not tell RA from RAV from RAVL. Measure, or read the letters on the old head or the valve. If you cannot tell, do not order the RAVL head on a guess. A wrong collar is a return, and one review of this head already describes a unit that did not open or close the radiator.
If my Danfoss valve is already M30, do I need a special head?
No. An M30×1.5 Danfoss-pattern body takes a normal M30 head. In this set that is the K-Eco at about £19.00, not the RAVL head at about £22.75. You do not need the RA, RAV, or RAVL article numbers once the thread is M30. You also do not need the Vaillant article 9712-00.500.
Should I buy another Danfoss head instead?
Buy another Danfoss head when the collar is RA or RAV, or when you specifically want Danfoss’s own M30 head. A Danfoss M30 listing was seen on amazon.co.uk and was not kept in this Heimeier comparison. Buy the Heimeier-style head in this set when the collar is RAVL and you accept seller part 27135 6, the Sanitop-Wingenroth brand line, and the plastic-claw comments in the reviews.
Related pages
Sources
Public sources are IMI head data, BS EN 215:2019, Approved Document L, the BEAMA installer factsheet, and Energy Saving Trust. Listings are the amazon.co.uk captures for these eight ASINs on 15 October 2026, not a live reload. Prices on amazon.co.uk move. A KEYMARK line on an IMI datasheet is not a mark on an ASIN that does not print it.
- IMI thermostatic head K (retrieved 15 October 2026)
- IMI heads for other manufacturers (retrieved 15 October 2026)
- IMI UK TRV pack Eclipse (retrieved 15 October 2026)
- BSI, BS EN 215:2019 (retrieved 15 October 2026)
- Approved Document L Volume 1 (retrieved 15 October 2026)
- BEAMA TRV factsheet (retrieved 15 October 2026)
- Energy Saving Trust, thermostats and heating controls (retrieved 15 October 2026)
- amazon.co.uk listings in this set (retrieved 15 October 2026)