Title: Vaillant VP5 Stove Error F75 - Pressure Sensor Compatibility & DIY Descaling Guide Needed

Hello
error F 75 has been popping up in my Vaillant Vp 5 stove for a long time, at first once a month, gradually, and now even twice a day, I suspect it's a pressure sensor, so I wanted to order it, but I'm not sure, because my sensor has no : 0020016532, and on websites after searching (e.g. in Amazon, Allegro) it shows me only the sensor number; 0020059717, will this sensor fit my Vaillant Vp 5 stove? can anyone advise me?
I also have such a request, because this furnace is scaled (I have no idea about furnaces at all) so I called (twice) a specialist from Vaillant to clean the furnace of scale, and he replied that the furnace is too much scaled and it cannot be descaled I need to buy a new furnace and he gave me offers of new furnaces, I think he is lying to me and wants me to buy a new furnace from Vaillant.
So I also have a request that someone write me step by step how I can clean it of scale, and I will do it myself.

Thank you in advance for your help and best regards

First of all, provide a detailed description of the boiler - the exact model, or take a photo of the rating plate.
Secondly, descaling can be done by yourself, provided that you have access to a rinsing pump and chemicals intended for it. You can always replace the calcified exchanger itself.
But the most important thing for now is to specify what kind of boiler it is because I do not know such a designation as you gave "VP 5".

It's hard not to be suitable, but we'll wait for info.
And I will add to that one more. when was the last solid maintenance?

Hello
Thank you for the quick reply, my stove is: Vaillant ecoCOMPACT/2

ls_77 wrote:

because I do not know such a designation as you gave "VP 5".

It's probably the inscription read from the circulation pump, because it only fits :)

ls_77 wrote:

Secondly, descaling can be done by yourself, provided that you have access to a rinsing pump and chemicals intended for it.

in home conditions, hardly anyone has a rinsing pump, but even without it, some boilers can be used for descaling.
More work but you can see the difference and the effect, so in my opinion it's worth improvising. Protective gloves are then required to protect against caustic cleaning agents.

marekkamcia wrote:

my stove is: Vaillant ecoCOMPACT/2

I am more interested in the type designation VUW and then numbers or letters at the end.
Although probably ls_77 distinguishes boilers by the name itself, it will tell you something more.

And where on the stove is the type of stove written?

Added after 17 [minutes]:

Unless I found this marking in the book: VSC 126/2-C 140, or VSC 196/2-C 150, maybe it's the type of furnace ?

Added after 4 [minutes]:

Ah, my stove is VSC 126/2-C 140, is it enough?

marekkamcia wrote:

my stove is a VSC 126/2-C 140

this is your model number.
So you have a boiler integrated with a 5.3-15.2kW tank for 40/30 boiler water.
Download the installation manual, it may help you a bit.
The magnesium anode in the storage tank needs to be replaced periodically to minimize the effects of corrosion.
I only descaled my Vaillant 2-function boiler, an old atmospheric one. I have no experience with containers, so I will not advise, because it would be improvisation for me anyway.
The most important thing is not to do it in a hurry and possibly have a set of original gaskets, because if you dismantle something, new gaskets are put on.

Last maintenance December 2017

Maintenance 1.5 years ago will do, every 2 years is a must.
Maybe I can hold off on this sensor a bit (I don't know why such a rush, the related faults are F 73.74)
For now do:
- thorough cleaning of filters,
- answer furnace - separator 16,
- fill up the water pressure, the pressure gauge should show approx. 1-1.5 bar,
- dismantle the pump13 and clean it,
- check bypass, patency,
- obvious that cleaning the siphon and flooding it with water.
- and check the expansion tank (expansion vessel if there is air in it 0.6 - 0.8 bar - at a pressure of 0.0 bar on the pressure gauge.).

Hurry? well, because I already have this glitch every day, and the sensor because I read it somewhere.
And if it comes to descaling, can it be done with vinegar? and can you describe it to me step by step how to do it? because I'm green in this topic ?

I did not manage to say that it is a condensing boiler with a built-in tank - the so-called refrigerator - a combination of a hanging condensing boiler with a HUW tank loaded in layers by a plate heat exchanger.
The reason for the F.75 error is most often calcification of the primary exchanger or, less frequently, an error of the pressure sensor, sometimes a seized pump, sometimes silting of the boiler. F.75 says that the boiler electronics did not read the pressure jump after starting the pump.
Like most Vaillant condensing boilers, it has a primary heat exchanger (flue gas-water) made of stainless steel. Such a "flattened tube" wound in the form of a drum, where the flowing water flows up and down - like on a roller coaster. This is what he looks like:

Alone at home, there may be a problem with descaling this exchanger. It is not very possible to flood it with some descaler, leave it and rinse it. There are too many nooks and crannies. A rinsing pump is useful, which constantly flushes out the sips that remain in the pump tank.
You can always replace the exchanger itself instead of the entire boiler - product code 0020135129 according to the catalog - at our cost ~ PLN 2,100.
You can also start with the pressure sensor itself - because the cheapest - product code 0020059717 according to the catalog - at our cost ~ PLN 90.

Look for the boiler rating plate - a sticker with the serial number.

And what does this exchanger look like? Can you send me a photo of it? And can it be descaled, for example, with vinegar and without this pump?

Added after 15 [minutes]:

So maybe I should try to descale it myself first?

I already posted a photo of the exchanger itself:

This is the "black drum with stainless steel inside".

Here are sample photos: link

This vinegar (or any other descaler) cannot be descaled by yourself.

You can add a cleaning fluid to the central heating system - pour it through a radiator - start central heating according to the liquid's instructions, wait the appropriate number of days, drain the water from the central heating system and the boiler, rinse thoroughly, sometimes a neutralizer or inhibitor should be added. That's the only way you can do it yourself.
From fluids you have:
FERNOX
SENTINEL
FERDOM

A softener as found - especially for boilers that heat DHW using a plate heat exchanger.
Vaillant VSC ecoCOMPACT - here too there is a plate heat exchanger for a stratified heat exchanger.

Please help me, maybe first with decalcification, how? and what? (and where to buy it?)

ls_77 already wrote you how and with what you can do it in post # 13, but it was similar earlier with a photo of the exchanger, you got a photo, and yet you asked for a photo of this exchanger.
For the Sentinel you have the mid X400 and with the Fernox you have the F3. Where to buy it, search on Google, probably somewhere in Berlin you can buy it.
Sorry, but with such questions on your part, I can't see how to handle this cleaning myself. Independent work requires some technical sense, and I don't see that in you.

But if you feel up to it, you can try, the means do not cost a fortune, and it is worth a try. In the worst case, you will buy a new boiler or exchanger anyway, so you will lose money + time spent.
For you, the first step is to get rid of the F.75 error, which may have several causes.
Cleaning the boiler and installation will certainly be useful, but it does not guarantee removal of this error, so you need to act systematically.
It is worth remembering that the primary exchanger is subject to contamination from the water side as well as from the fire side. Then you have a secondary heat exchanger. plate heats hot water and it has 2 circuits with boiler water and tap water, which are isolated from each other, so cleaning this plate exchanger requires its disassembly.
In addition, we do not know what condition the tank itself is in, or whether it also needs cleaning.
There is quite a challenge ahead of you, because I don't know if I would be able to cope with it, because many elements would be new to me.
But since the boiler is already referred to as a corpse, it's worth trying, because you can extend its life by a few years.
Boiler cleaning is time-consuming and labor-intensive, which is why service technicians are reluctant to sign up for such work, because the bill would have to be considerable, and it does not guarantee that the boiler will work for a long enough time worth the money spent. It is easier and safer for the service technician to persuade the customer to buy a new boiler.

If you buy a new condensing boiler, in my opinion it is worth installing the so-called desilter, a filter with magnets that filters the central heating system and protects the boiler from deposits, which can extend the operation of the boiler without surprises.
I don't have a filter, but I regularly clean my atmospheric boiler, thanks to which there is no situation that the boiler refuses to obey due to contamination from the fire side or from the water side.

A way:
1. drain the water from the nearest radiator to the stove
2. close the valves of the remaining radiators on the manifold
3. flood the radiator with descaler, e.g. FERNOX , SENTINEL , FERDOM or KROFIX
4. fill the system (stove-radiator) with water to approx. 1.2 bar, vent
5. Start the stove in the heating function at a temperature of about 40 degrees for about 3 h in intermittent mode
6. empty the system (stove-1 radiator), clean the filters and rinse with clean water
7. rinse the remaining radiators with clean water, clean the filters
8. fill the entire system with clean water with an inhibitor to approx. 1.2 bar, vent.

B. way when there are no manifold valves:
1. we proceed as above, except for point 1,2,3
2. drain the water from the stove itself, unscrew the expansion vessel in the stove
3. using a funnel, pour into the tube after the diaphragm vessel, e.g. FERNOX , SENTINEL , FERDOM or KROFIX (quantitatively you need to use more)
4. reinstall the expansion vessel
5. Top up the system with water (stove-radiators) to approx. 1.2 bar, vent
6. start the stove in the heating function at a temperature of about 40 degrees for about 6 h in intermittent mode
7. Drain the system, clean the filters and rinse with clean water
8. other activities as above point. 7-8

You can still do it with a "bypass", but it requires caution, but the rest of the installation also needs to be cleaned.

Erbit wrote:

I confirm (seeing what the service technician was doing) that I wouldn't do it myself - unless I had to.

Having a vision of replacing the boiler with a new one, it is probably worth trying and getting tired, at least there is something to fight for.
Only the case is different when we clean the boiler every year or every 2 years, and otherwise if we let it overgrow with deposits, because then the problem is bigger.
When I tried to dismantle my boiler for the first time, I wanted to chop it with an ax, because disassembling the secondary exchanger was a challenge, but it was enough to think and use an intelligent solution instead of a force one and everything went without destroying any tube, etc..
It must also be taken into account that not everyone has free space around the boiler, some have built-in boilers, which only complicates cleaning, etc.
Privately, I can pick at least 2 days with peace of mind, because no one and nothing is chasing me.
My primary exchanger on the fire side is nice to clean with a karcher, but it requires a trip to a manual car wash, unless someone has a plot and has their own karcher, it's easier.

ROWE wrote:

3. flood the radiator with descaler, e.g. FERNOX , SENTINEL , FERDOM or KROFIX
4. fill the system (stove-radiator) with water to approx. 1.2 bar, vent
5. Start the stove in the heating function at a temperature of about 40 degrees for about 3 h in intermittent mode

According to the instructions, the Sentinel X400 can be in the installation for up to 4 weeks, so 3h is in my opinion a bit too short for a boiler and installation that has never been cleaned.
If the installation has never been cleaned, I would pour X400 for a few weeks, because X400 is not a Kamix that can eat something.
Only this makes sense during the heating season, because now no one will specifically drop the boiler and heat it when it's about 8 p.m. outside the window.

Well, now the boiler does not fire, but the stove heats the washing water, so it must also be turned on?

In general, thank you very much for the advice that will certainly help me, if anyone else would like to give me a hint, please do.
Thanks again and best regards to all

Added after 11 [minutes]:

One more thing, and how many liters should I buy this descaler?

marekkamcia wrote:

Well, now the boiler does not fire, but the stove heats the washing water, so it must also be turned on?

now the boiler only heats hot water, but if you pour, for example, X400, it would be appropriate for the agent to rinse the entire installation, i.e. also radiators and valves, etc.

marekkamcia wrote:

How many liters should I buy this descaler?

X400 requires at least a concentration of 1%, i.e. 1 liter is sufficient for a maximum of approx. 100 liters of water in the installation.
You need to count more or less how much water your radiators and pipes from the installation have, what after summing up you will know what your water volume is and whether 1l is enough for you.

Thank you for your help

Added after 5 [hours] 53 [minutes]:

And what is the difference between this liquid x 400 and others x800 or x600?

read in the net.
From the description, the X800 looks more "corrosive", because it is supposed to be in the installation for about 1 hour.
X600 I don't know, maybe you meant X500, which is a la X100 corrosion inhibitor with an additional freeze protection option.
The X300 is dedicated to new installations less than 6 months old and the X400 is for installations older than 6 months.

Approx
Thank you

You can also use the Sotin 212 agent. You close the valves behind the boiler (supply and return) with the drain drain, empty the exchanger and finish off the drain with any piston pump for several dozen zlotys, which sucks the liquid with one entrance and pumps the liquid with the other. You turn on the bleeding program so that the pump spins around the internal circuit nicely .... that's all the work you can still run the boiler on minimum gas for a while to heat the elixir

Hello
I also have a problem with the F.75 error in the furnace
VCW PL 296/3-5
The error appeared more and more often until it latched permanently
the stove was descaled
the problem subsides for a while, I will move the pump's vent or add water
So I thought it was a problem with the pressure sensor
Does the stove catch the pressure jump from the sensor that shows the pressure in the installation or is it separate to confirm the flow?

It's the same sensor.

Hello
Thank you all for the very helpful information provided. I have a similar problem, also with a boiler with a built-in hot water tank. One additional question - error F75 appears only when the boiler works for the needs of which hot water does without any problems. The central one manages to start after letting water into the heating system, although the pressure is still high. Cold water to the boiler comes from the station treated and is clean. The heating installation (pipes, radiators, boiler) was descaled some time ago, although it ended with a large leak from the boiler and radiators.
Should you start with this procedure in this situation:
- thorough filter cleaning,
- vent the furnace - separator 16,
- fill up the water pressure, the pressure gauge should show approx. 1-1.5 bar,
- dismantle the pump13 and clean it,
- check bypass, patency,
- obvious that cleaning the siphon and flooding it with water.
- and check the expansion tank (diaphragm vessel if there is air in it 0.6 - 0.8 bar - at a pressure of 0.0 bar on the pressure gauge.).
Regards and thanks for your help
Simon

>>19581698
How did your adventure with repair end? I have identical symptoms. Kamix exchanger descaled, pressure sensor replaced, installation vented. When the shut-off valves are closed, it catches a pressure jump, and when it is open, most often F75.