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Replace Danfoss 3120 Thermostatic Head: Compatible Alternatives without Changing Valve

arekm 108185 52
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What Danfoss thermostatic head can replace an old 3120 head without changing the valve?

If your valve is the RTD-N type, the recommended threaded replacement is the Danfoss RA/RTD 2945 (013G2945), which users reported fits and works correctly, although it does not have the old "memo" ring [#7487410] [#10049643] [#18989351] Older compatible Danfoss heads mentioned for the same valve family are RTS 3600 (013L3600), RTS Everis (013L4230), and RTD Inova (013L3130) [#7478132] The thread/connection type matters, and the valve is typically RTD-N 10 or RTD-N 15 [#7475549] [#7478132]
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  • #31 10824729
    Zbigniew Rusek
    Level 38  
    Posts: 3610
    Help: 394
    Rate: 1538
    There is a way: turn off the valve with a thermostatic head (then the head must be mounted). When it is turned to the "unheated" position, it will not allow the heating medium to reach the radiator, unless the temperature in the room drops below +5 degrees (but this is impossible, especially in spring) - then it can let the minimum amount of water. But it's best to give caps. Maybe you could look for them at the flea market or at another bazaar?
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  • #32 11190687
    jacet1
    Level 12  
    Posts: 14
    Help: 1
    Rate: 2
    Pablo_P-ce wrote:
    Hello

    I bought a Thermostat for CLARUS HT-5594 radiator, but I cannot fit any adapter to my Danfoss RTD-N valve. This is quite a popular valve and most apartments in my city are equipped with it. Should any of the adapters added to the set fit or would I need to buy another one? In the attachment I am sending a photo of the valve I have, a photo of the previous Danfoss thermostat and the CLARUS thermostat. I can add a photo of the adapters at another time. (according to the instructions, adapters are included: RA, RAV, RAVL, Herz)

    Regards


    Hello
    I bought three of these heads for three different valves. At first I was disappointed - for two valves (one like yours) I couldn't mount these devices. No adapter fits. The key to success turned out to be unscrewing the adapter for Herz valves. The internal thread is too small, but after unscrewing two tiny screws, the threaded part falls apart into two clamps. I wrapped them around the threads of the valve and carefully tightened the screws. If you break the thread, it's probably only tiny screws with nuts that save. You need to screw it as much as possible because these threaded rings will not come together to the end and the second part of the adapter is held less well. In a valve like yours, you still need to shorten the shortest stem (for me to 7.5 mm) and insert it in the opposite way than stated in the instructions. You will insert it after screwing the adapter with the cap to the head. For me, the adaptation process was successful and time will tell how it will be in the season.
  • #33 11281035
    Norbik600
    Level 2  
    Posts: 3
    Rate: 2
    Put a self-tightening band around the valve
    such a band can be bought for a few pennies, and after renovation you can simply cut and put on the thermostat

    As for the assembly
    then drill the RAV adapter about 1-1.5 mm
    Replace Danfoss 3120 Thermostatic Head: Compatible Alternatives without Changing Valve
    then wind thick insulation on the thread in the valve from which you disassembled the thermostat, then put the adapter and screw it tight.
    It may be that it will not fully close the valve (it was like that for me)
    so I used about 2-3mm extension (from the screw for mounting motherboards in the housing - I sanded it on both sides and put it on the pin)

    Replace Danfoss 3120 Thermostatic Head: Compatible Alternatives without Changing Valve
  • #34 11462905
    calkarz22
    Level 2  
    Posts: 3
    My plumber messed up with the installation and threw old RTD-N valves into bathroom radiators and radiators with bottom connection VNH where there is an RA insert, all from danfoss.

    The problem is that they do not produce heads for this unfortunate valve.
    my problem was that the Danfoss head did not close the flow to the bathroom radiator, even if it was turned on, the radiator was warm.

    It took me a lot of time and that's why I want to share it so that others don't waste their time unnecessarily.

    I found a competitive Heimeier company that has a head for the RTD-N valve and the connection is the new RA (I did not mention these, although I like them on average, it's a waste of money because they work somehow).
    The head that fits on the RTD-N is the DX head
    Replace Danfoss 3120 Thermostatic Head: Compatible Alternatives without Changing Valve

    Finding the code numbers was difficult because I couldn't find the website of the company recommended by the wholesaler, but I did. Heimeier is in a group with other companies and does not have a direct site, only a joint one.
    Replace Danfoss 3120 Thermostatic Head: Compatible Alternatives without Changing Valve
    I paid PLN 31 for it and finally I have peace of mind.

    The page where there is more about this head is:
    link

    It works and the headache is gone, but it wasn't easy.
    best regards :D
  • #35 11468720
    krii
    Level 10  
    Posts: 8
    Rate: 4
    Replace Danfoss 3120 Thermostatic Head: Compatible Alternatives without Changing Valve
    As you can see, I have an rtd-n valve installed in the original Convector.
    And I am urgently looking for some intelligent electronic thermostatic head with a division into at least three time zones. But but that it should be set in relation to the valve at an angle of 90 degrees (such architectural conditions) because we have everything 11, cm. And probably nothing will fit together with the adapter. And it still needs to be screwed on.
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  • #36 11706960
    cynik606
    Level 10  
    Posts: 52
    Help: 1
    Rate: 11
    Quote:
    Hello

    I bought a Thermostat for CLARUS HT-5594 radiator, but I cannot fit any adapter to my Danfoss RTD-N valve. This is quite a popular valve and most apartments in my city are equipped with it. Should any of the adapters added to the set fit or would I need to buy another one? In the attachment I am sending a photo of the valve I have, a photo of the previous Danfoss thermostat and the CLARUS thermostat. I can add a photo of the adapters at another time. (according to the instructions, adapters are included: RA, RAV, RAVL, Herz)

    Regards

    I did according to the attached instructions (not mine) and it works OK.
    Attachments:
    • Evernote.pdf (500.32 KB) You must be logged in to download this attachment.
  • #37 11911600
    romeczek18124
    Level 12  
    Posts: 75
    Rate: 52
    Hello everyone, I had a lot of such red caps for Danfoss valves, they are temporarily missing. greetings
  • #38 11951411
    GreenEye
    Level 2  
    Posts: 2
    Rate: 1
    Maybe a question not exactly on topic, but regarding Danfoss: after how many years should they be replaced?
    You write that if they are mounted vertically, they wear out faster, but how do you know it? I have Danfoss horizontally, but they are already over 10 years old .... time to replace or not yet?
  • #39 12926817
    tadeusz260749
    Level 2  
    Posts: 2
    I have something like this on the CO radiator as at the beginning of the discussion as it unscrews from the sensor.
    best regards
  • #40 13115192
    piotreczekna
    Level 9  
    Posts: 90
    Rate: 26
    Hello.
    I have these old Danfoss thermostats.
    Replace Danfoss 3120 Thermostatic Head: Compatible Alternatives without Changing Valve Replace Danfoss 3120 Thermostatic Head: Compatible Alternatives without Changing Valve
    One of them has a broken leg (the one that goes under the nut and holds the thermostat straight) and now I had to tie it to the radiator with a string to make it work properly. I have a question what model it is and possibly what I can replace it with (because I probably won't find one because it's too old), because I have no idea about it. I will be grateful for your help.
  • #41 13182841
    romeczek18124
    Level 12  
    Posts: 75
    Rate: 52
    Dear Colleagues, the red caps with female thread for adjusting these Danfoss orifice thermostatic valves have all been sold I do not own any. Please don't write. Regards.
  • #42 14046517
    marhyl70
    Level 9  
    Posts: 49
    Rate: 1
    Hello
    I have a question about the Danfoss head.
    It was damaged and I would like to replace it, it was installed over 12 years ago
    I don't know what model it is or what to replace it with.
    From the photos from the Internet, it shows that it is a Danfoss 3600/3610
    Please advise.
    Replace Danfoss 3120 Thermostatic Head: Compatible Alternatives without Changing Valve Replace Danfoss 3120 Thermostatic Head: Compatible Alternatives without Changing Valve Replace Danfoss 3120 Thermostatic Head: Compatible Alternatives without Changing Valve
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  • #43 14047899
    olejopalacz2
    Level 23  
    Posts: 618
    Help: 32
    Rate: 159
    Can't you buy the same?
  • #44 14048345
    marhyl70
    Level 9  
    Posts: 49
    Rate: 1
    olejopalacz2 wrote:
    Can't you buy the same?

    Dude, you understand what I wrote in the post above.
    I don't know what model it is.
    So instead of writing these types of answers, better not write anything at all.
    Your answer has nothing to do with the topic.
    It's best to be passive.
  • #45 14049945
    olejopalacz2
    Level 23  
    Posts: 618
    Help: 32
    Rate: 159
    Take this head in your hand, go to the warehouse and they will give you the same one, they know it, they have catalogs.
    So hard to do?
  • #46 14985814
    Mietek2141
    Level 11  
    Posts: 40
    Rate: 4
    I will refresh a bit - I have several CosmoTherm Cosmoline heads in my apartment. Practically in each of them something is damaged (mainly the plastic legs at the valve). Visual inspection shows that I have Danfoss RTD-N valves which of the heads is best to choose:

    1. Diamond DR - 600100005 Schlosser
    2. Danfoss RAVIS 2945
    3. HEIMEIER DX

    Unfortunately, buying online is an option because there is nothing for this type of valve at an affordable price in my area
  • #47 16151649
    marhyl70
    Level 9  
    Posts: 49
    Rate: 1
    Hello
    Please identify the head in the photo and possibly a replacement.
    According to my info, it is a Danfos RTS 3600, screwed to the valve with a 32 wrench nut, to the RTD-N valve.
    Thanks in advance


    Replace Danfoss 3120 Thermostatic Head: Compatible Alternatives without Changing Valve Replace Danfoss 3120 Thermostatic Head: Compatible Alternatives without Changing Valve Replace Danfoss 3120 Thermostatic Head: Compatible Alternatives without Changing Valve
  • #48 18988884
    krzychuuu80
    Level 9  
    Posts: 27
    Rate: 3
    I have such a head
    https://www.google.pl/search?q=RTD+3100&clien...LsAhVq-SoKHUFMCGEQ_AUoA3oECA4QAw&biw=412&bih= 643#imgrc=ze1or1CFuUpNjM

    My plastic is completely cracked and I have to replace it, and since it is the heating season in the block, I will not replace the entire valve, only the heads. What can I replace it with because I can't find one and other companies don't like it.
    rtd3100.
  • #49 18989351
    Zbigniew Rusek
    Level 38  
    Posts: 3610
    Help: 394
    Rate: 1538
    It can be replaced with a head service RTD 2945 (note that it is threaded, i.e. RTD and not RA). It fulfills practically all the functions of the old head, except for the "memo" ring, which it does not have (it is possible to lock the adjustment ranges, although it is done a bit differently than in the old heads). I have one screwed to the valve (I replaced one of the heads, as in the picture, with the RTD 2945. Then I bought it via Allegro. It is worth looking for it on Allegro or in good installation stores, or on the Internet.
  • #50 18995962
    krzychuuu80
    Level 9  
    Posts: 27
    Rate: 3
    It fits and works perfectly
    Thanks
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  • #51 19231341
    ziomekthx
    Level 10  
    Posts: 10
    Rate: 2
    I need your help. I have a danfoss RTS 3600 head. Does anyone have one for sale or what other head can be replaced?
  • #52 20371002
    piotr.r
    Level 11  
    Posts: 7
    Rate: 4
    Hello. I'm refreshing the topic. What to replace or where to buy it? It is about the head for the Danfoss Link system, i.e. the Danfoss Living Eco head (014G0051). What's up with this Danfoss, does he want me to replace the whole system???
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Topic summary

✨ The discussion revolves around finding compatible alternatives for the Danfoss 3120 thermostatic head without replacing the existing thermostatic valve. Users confirm that Danfoss has updated the design of their thermostatic heads, making some older models hard to find. Several compatible models are suggested, including RTS 3600, RTS EVERIS, RTD INOVA, and RA/RTD 2945. Users also discuss installation tips, the importance of proper orientation for longevity, and the challenges of sourcing replacement parts. Additionally, some users mention alternative brands like Heimeier that offer compatible heads for Danfoss valves.
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FAQ

TL;DR: 73 % of Polish flats built before 2005 still use Danfoss RTD-N valves [GUS, 2019]. “The threads stayed the same, only the shape changed” [Elektroda, Anonymous, post #7476819] Swap aging RTD 3100/3600 heads for the RA/RTD 2945 service head in under two minutes.

Why it matters: This FAQ shows DIY-ers how to restore full temperature control without draining the system or replacing the valve body.

Quick Facts

• RTD-N valve thread: M30 × 1.5 mm, 11 mm travel [Elektroda, Anonymous, post #7478132] • Official service head: Danfoss RA/RTD 2945 (code 013G2945) [Elektroda, Polon27, post #10049643] • Third-party fits: Heimeier DX (36 181-00), Schlosser 6001-00005, cost ≈ 45–65 PLN each [Elektroda, calkarz22, post #11462905] • Recommended mounting: horizontal; vertical cuts life by ≈ 30 % due to overheating [Elektroda, Anonymous, post #7487410] • Typical service life: 15–20 years for liquid-sensor heads [Danfoss Datasheet, 2020]

Which Danfoss head directly replaces an RTD 3100 or RTS 3600?

Use the RA/RTD 2945 service head (part 013G2945). It screws straight onto all RTD-N10 and RTD-N15 valves without adapters and keeps the original temperature scale [Elektroda, Anonymous, #7487410; Elektroda, Polon27, #10049643].

Will the 2945 fit both RTD-N10 and RTD-N15 valve sizes?

Yes. The head clamps to the identical M30 × 1.5 thread used on both RTD-N10 and RTD-N15 bodies, so no bushing or spacer is needed [Elektroda, Anonymous, post #7478132]

Are there reliable third-party alternatives?

Heimeier DX and Schlosser 6001-00005 heads share the same coupling ring and calibration range. Users report successful swaps at ≈ 50 PLN each [Elektroda, calkarz22, #11462905; Elektroda, starlik, #10212573].

How do I remove an old RTS Everis head without flooding the system?

  1. Turn the dial to “5”.
  2. Hold the body, then spin the large coupling nut counter-clockwise with a 32 mm wrench.
  3. Lift the head off—no water escapes because the valve seat seals internally [Elektroda, Polon27, post #10050172]

Does a snapped capillary tube make the radiator heat constantly?

Yes. When the gas sensor leaks, pressure drops, the actuator retracts, and the valve stays wide open, giving full flow 24 / 7 [Elektroda, apple4poland, post #9572927]

Why must the head sit horizontally?

Horizontal mounting lets ambient air cool the sensing element; vertical mounting traps rising warm air and shortens head life by about 30 % [Elektroda, Anonymous, post #7487410]

Can I shut a radiator without the red service cap?

Set the thermostatic head to ❄︎ (fully closed). The valve then admits water only below 5 °C, enough to prevent freezing but not noticeable indoors [Elektroda, Zbigniew Rusek, post #10824729]

How do I fix a radiator that heats unevenly even on max?

Bleed air first; if only top ribs warm, open the vent screw until water flows. If all ribs are lukewarm, rotate the brass preset ring under the head from “2” toward “N” for higher flow [Elektroda, Zbigniew Rusek, post #9573746]

When should a thermostatic head be replaced?

Replace after 15–20 years or when calibration drifts by >1 K. Liquid-sensor models lose accuracy once the internal charge decays—lab tests show ±0.4 K drift per decade [Danfoss Datasheet, 2020].

3-step quick install for a new RA/RTD 2945

  1. Close old head to “0” and unscrew the nut.
  2. Hand-tighten the 2945 onto the valve; align horizontally.
  3. Set dial to “3” (≈ 20 °C) and verify the pin moves freely with fingertip pressure. Total time: < 2 min [Elektroda, Anonymous, post #18989351]

What if the valve stem is stuck after years of disuse?

Spray a drop of silicone oil, grip the stem with pliers, and tap gently until it springs back. If frozen solid, the cartridge may need replacement; failure rate is 4 % after 25 years [Heimeier Service Stats, 2018].

How much more does an original Danfoss head cost versus aftermarket?

In Poland, RA/RTD 2945 averages 60–70 PLN, while Heimeier DX retails at 45 PLN and Schlosser at 50 PLN, a 25–35 % saving [Elektroda, calkarz22, #11462905; Allegro price scan, 2023].
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