How do I automate a DC fan with 15/15 min mode at negative temperatures?

Good afternoon, I am looking for a solution to the following issue.

I have a fan (DC) running in continuous mode. I would like to connect it to some kind of controller which, when negative temperature is detected, would switch it to power with a timer running 15 mins on, 15 mins off, and which would return to continuous operation when the temperature rises.

The idea is to achieve this effect: when the outside temperature is positive, the fan runs continuously, when it is negative it runs in 15 min on/off mode.

I wanted to do this with a temperature controller , timer and automatic power regulator , which would switch to an alternate power supply with a timer after a loss of voltage from the temperature controller, but maybe there is a simpler way, because here I have as many as three devices?

He who seeks does not wander :

just take a look here and choose the right finished product available on the market.

For example, the AR603 temperature controller should meet your needs:
" time function (clock):－start signal: button or binary input START/STOP, power on

－start of timing: after start signal or when heating setpoint is reached
－supervised outputs: P1/SSR1, P2/SSR2
－indication of timer operation: LED TIME, output P2/SSR2
－setting range: 0 ÷ 8640 minutes (up to 144 hours) ".

aaanteka wrote:

Who seeks does not wander :

just look here and select the appropriate finished product available on the market.

For example, the AR603 temperature controller should meet your needs:
" time function (clock):－start signal: button or binary input START/STOP, power on

－start of timing: after start signal or when heating setpoint is reached
－supervised outputs: P1/SSR1, P2/SSR2
－indication of timer operation: LED TIME, output P2/SSR2
－setting range: 0 ÷ 8640 minutes (up to 144 hours) ".

Well something like that, except that the price is also knocked down. How about something like this: PCU-507 + temperature controller, about like this: http://allegro.pl/termostat-regulator-temperatury-50-110-i6059974214.html

A total of 150 zł.

This can be solved in different ways.

But what you have indicated plus power supply, housing, problems with commissioning (often such kits have a leaky sensor system, are not refined, have manuals, you have to reckon that the first system will go to the trash:D ), is the cost of similar or even greater if you add the cost of purchase in various online shops.

aaanteka wrote:

It can be solved differently.

But what you have indicated plus power supply, housing, problems with commissioning (often such kits have a leaky sensor system, are not refined, have a manual, you have to reckon that the first circuit goes to the trash:D ), is the cost of similar or even greater when you add the cost of purchase in various online shops.

I quoted £150 including delivery costs. The power supply for the sensor is £10 including delivery. The housing is a 30 min job. Instead of such a temp sensor it could already be with a housing for 100 zł and still be 230, not 400.

I do not understand, either the parameters or the savings and lack of indicated parameters and repeatability.
How about a general use of an on/off switch, an egg timer, a round thermometer and an attendant?

I see that a colleague has changed his entry, maybe in other words exactly what is the fan for, what type of power supply, size?

aaanteka wrote:

I do not understand, either the parameters or the savings and lack of indicated parameters and repeatability.
Maybe generally use an on/off switch , an egg timer , a round thermometer and an attendant?

I see that a colleague has changed the entry, maybe otherwise exactly what is this ventilator supposed to be for?

In the entry I just added a drawing, kind of illustrative. OK, so here's the thing: in recuperators there's a marvel called the "anti-freeze system" - this "technical marvel" is implemented in several ways, and each time is then sold for a lot of money. One way is to temporarily switch off the supply fan while the exhaust fan is always running. This way, when the temperature is negative, the warm air from the building heats the exchanger defrosting it or not allowing it to freeze at all. The blower fan simply pauses every 15 min for 15 min when the temperature is below 'some' (implicitly negative). The more 'fabulous' recuperators still have pressure switches to detect negative pressure - that's the magic of 'anti-freeze systems' for which you pay extra, e.g. £1,000.

What you think is simple in concept, yes it is, but in the final implementation it requires a bit more resources and time, a bit more than 1k pln (on average somewhere 1000 times more ).
A well made and working recuperator is quite a challenge to realise - even if you assemble it from ready made "blocks" .
I still don't know what we are talking about, from the schematic - sketch it looks like your colleague wants to use some kind of DC motor?
Not really suitable for exchange systems due to the speed, unless you use its properties for easy adjustment .

Is this to be a mini recuperator or has your colleague also come up with an ingenious solution?
Or maybe a mega-sized recuperator for the production hall , which would then explain the use of centrifugal fans with a gear drive DC motor (occasionally used nowadays due to drives with inverters not destructible) .

Where did the colleague get the 15-minute defrost period from? At winter temperatures for our latitude, it may turn out that "defrosting the recuperator" and the recuperator itself will cool down the room while consuming energy .

aaanteka wrote:

Kolego what according to you in the idea seems simple yes it is, but in the final implementation requires the sacrifice of some resources and time, a little more worth than 1k pln (on average somewhere 1000 times more ) .
A well made and working recuperator is quite a challenge to realise - even if you assemble it from ready made "blocks" .
I still don't know what we are talking about, from the schematic - sketch it looks like your colleague wants to use some kind of DC motor?
Not really suitable for exchange systems due to the speed, unless you use its properties for easy adjustment .

Is this to be a mini recuperator or has your colleague also come up with an ingenious solution?
Or maybe a mega-sized recuperator for the production hall , which would then explain the use of centrifugal fans with a gear drive DC motor (occasionally used nowadays due to drives with inverters not destructible) .

Where did the colleague get the 15-minute defrost period from? At winter temperatures for our latitude it may be that the "defrosting of the recuperator" and the recuperator itself will cool down the room consuming energy .

This is not to defrost the recuperator just to prevent frosting, in effect clogging the heat exchanger. If frost has built up in 15 minutes of "sucking in" cold air, then 15 minutes of blowing warm air through the recuperator in an attic where the temperature is positive should "defrost" it. Although a good point, perhaps the air supply should only stop once every hour for 15 minutes.

The recuperator is supposed to be "mini", based on such fans: http://allegro.pl/noctua-nf-a14-industrialppc-3000-pwm-269-3-m3-h-i6005634349.html (yes, yes I'm not joking), according to this manual: http://www.builditsolar.com/Experimental/DIYHRV/DIYHRV.htm

And after reading this topic (50 pages of interesting reading, with 3 realised and working recuperators): http://ecorenovator.org/forum/conservation/891-diy-ventilation-heat-exchanger.html

By mini I mean a volume of 180 m3, two extractors, two supply air - each point no further than 3.5 metres from the air handling unit. Outside air and exhaust not more than 4 metres from the air handling unit. AHU in the attic, insulated ducts routed in the sheathing in additional insulation.

kurdebele666 wrote:

Through this, when the temperature is negative, the warm air from the building warms the exchanger defrosting it

kurdebele666 wrote:

This is not to defrost the recuperator only to prevent frosting, in effect clogging the heat exchanger. If frost has built up in 15 minutes of "sucking in" cold air, then 15 minutes of blowing warm air through the recuperator in an attic where the temperature is positive should "defrost" it.

I don't know why use an expensive PWM controlled fan to then switch it on periodically?
It is better to use cheaper fans available on the market, not the supposedly quiet ones, but so quiet that the manufacturer himself does not specify their volume in dB ( the reason is probably one thing, they are quieter by less than 3dB than the usual cheap ).
And invest the cash in a precision regulator.

For example, have you considered the performance of the AAB COOLING SUPER SILENT FAN 25 fan? In comparison, your leader presents itself as a "noisy hooligan" <br/span> .

If you want to have a quieter one, use slow-running centrifugal fans (compared to axial propeller fans) as in the indicated articles. However, these tend to be more expensive.

aaanteka wrote:

kurdebele666 wrote:

Through this, when the temperature is negative, the warm air from the building warms the exchanger defrosting it

kurdebele666 wrote:

This is not to defrost the recuperator but to prevent frosting, in effect clogging the heat exchanger. If frost has built up in 15 minutes of "sucking in" cold air, then 15 minutes of blowing warm air through the recuperator in an attic where the temperature is positive should "defrost" it.

I don't know why use expensive fans with PWM control to then switch them on periodically?
Use the cheaper fans available on the market, not the supposedly quiet ones, but so quiet that the manufacturer himself does not give their volume in dB ( the reason is probably one thing, they are quieter by less than 3dB than the usual cheap ).
And invest the cash in a precision regulator.

For example, have you considered the performance of the AAB COOLING SUPER SILENT FAN 25 fan? In comparison, your leader presents itself as a "noisy hooligan" <br/span> .

If you want to have a quieter one, use slow-running centrifugal fans (compared to axial propeller fans) as in the indicated articles. But these are sometimes more expensive.

The fan I have specified has: Airflow: 269.3 m3/h
ABB: 64 m3/h

Pressure: 10
ABB: approx. 1

Loudness max. of mine 41 dB, ABB 13. Here it wins, but this is insufficient air volume (I need 3 times as much). So the one I specified can easily run at "half power" - it will be much quieter and the performance I am aiming for will be maintained. Unfortunately not many people specify the pressure

Centrifugal fans take a sick amount of energy, have massive compression and many times more airflow than I need.

Can you recommend/suggest any precision regulator that would be suitable for controlling such fans? Typing PWM on allegro I get a lot of results, but I don't know what to follow, something like this? http://allegro.pl/regulator-obrotow-silnika-dc-pwm-softstart-12v-20a-i6207415167.html

Added after 19 [minutes]:

What if, on top of all this, you added such a marvel and switched on the whole "recuperator" only when the humidity rises above 60 percent, the threshold for optimal humidity in a residential house?

I don't know if the humidity "expelled" with the used air would coincide or be close to the co2 level at which the ventilation should switch on, but I suspect it would.

kurdebele666 wrote:

The fan I specified has: Airflow: 269.3 m3/h
ABB: 64 m3/h

Pressure: 10
ABB: approx. 1

I don't know where a colleague found such data,but the fan I indicated has :
"Technical specifications:
RPM: 800 ± 10% rpm.
Power supply: 12V, 0.12 A
Flow: 232 m3/h, 133CFM
Weight: 215g
Noise: 14.9 dB
Thermal resistance:
Size
0.29 C/W
218 x 218 x 30mm'.

As for the performance and other parameters of Austrian manufacture I would argue , most are marketing gimmicks.
In server rooms they do not perform well despite claims.

I don't know what parameter would regulate the fan speed and for what purpose.
Measuring humidity is a completely bad idea.
The simplest suggestion is to abandon the existing concept and use a hydrophobic surface and cyclic heating with heaters.
This saves energy - the heaters mean negligible losses and, moreover, do not effectively allow frosting.

aaanteka wrote:

kurdebele666 wrote:

The fan I specified has: Airflow: 269.3 m3/h
ABB: 64 m3/h

Pressure: 10
ABB: approx. 1

I don't know where a colleague found such data,but the fan I indicated has :
"Technical specifications:
RPM: 800 ± 10% rpm.
Power supply: 12V, 0.12 A
Flow: 232 m3/h, 133CFM
Weight: 215g
Noise: 14.9 dB
Thermal resistance:
Size
0.29 C/W
218 x 218 x 30mm'.

As for the performance and other parameters of Austrian manufacture I would argue , most are marketing gimmicks.
In server rooms they do not perform well despite claims.

I don't know what parameter would regulate the fan speed and for what purpose.

And, I searched for the wrong fan. The one you mention yes, but there is no word on static pressure.

aaanteka wrote:

Measuring humidity completely wrong idea .

Because? Recuperation is nothing more than ventilating a room only with heat recovery. Why should I ventilate a room at all? After all, it's not to be ventilated, it's to get rid of moisture and the co2 accumulated by exhaling, incidentally any odours from the house. Why do I need to "ventilate" the house continuously if, for example, the humidity (I assume a priori and the co2 level) is normal? It's just blowing out stale air (but including heat) for backup.

aaanteka wrote:

The simplest suggestion is to abandon the existing concept and use a hydrophobic surface and cyclic heating with heaters .
This saves energy - the heaters are negligibly small losses and, moreover, do not effectively allow frosting.

I don't understand what you mean. Should I use a pre-heater? The simplest one takes 600 watts.

It seems to me that controlling the whole thing via a humidity sensor is a hoot - I'm ventilating the room according to need (demand), not in the name of 'air exchange', which in itself makes no sense....

Heating elements in the form of heating films, thick-film resistors, resistance heaters in the form of tape are used, as are fins of cooling systems, aircraft wings, helicopter rotor blades and similar applications.
Example implementation of such elements;

Of course, this requires a suitable implementation of the entire device.

Added after 6 [minutes]:

How do you imagine the implementation on the hygrometer? Because I don't really understand how to make something like that with variable parameters of the input medium (air) quite large hysteresis of the system tripping , while maintaining high efficiency of energy recovery?

aaanteka wrote:

Similar to cooling fins, aircraft wings, helicopter rotor blades and similar applications, heating elements in the form of heating films, thick film resistors, resistance heaters in the form of tape are used.
Example implementation of such elements;

Of course, this requires a suitable implementation of the entire device.

Added after 6 [minutes]:

How do you imagine the implementation on the hygrometer? Because I don't really understand how to make something like that with variable parameters of the input medium (air) quite large hysteresis of the system tripping , while maintaining a high efficiency of energy recovery?

1. These heating mats are as a pre-heater? It makes sense, but eats up energy. The recuperator should defrost the exchanger "by itself", using the used and heated air from the house - probably more economical that way?

2. How I imagine the whole system works. So:

A) the whole thing is connected to a remote contact (radio control - £23 + remote control £28), when you want to ventilate the house with heat recovery it does a "snap" and the ventilation starts running at the speed set on the controller (it's possible that this ABB is a better solution although I still have concerns about its "pressure").

B) regardless of being able to turn the system on demand, the fans are connected to the power supplies, these to the speed controller and this to the AVT1855 board. I set a value of 40 or 50 per cent humidity on the board, and when this value is exceeded the system turns on until the humidity is 'pulled' from the house to the optimum value.

Independently of A and B, there is a 'safety' circuit which checks the air temperature just before it enters the recuperator and when it detects a value of, say, -1 deg it switches the air intake fan to run intermittently (as a colleague suggested 15/15 is probably not a good idea).

Unfortunately such a system has a certain imperfection. A situation where, for example, it is constantly below freezing outside (e.g. 12 or 24 hrs) and the system only switches on to 'blow the moisture out' can lead to a situation where air is being pulled out of the house and not blown in. Assuming that the house is airtight, a negative pressure will be created which will "pull" cold air into the house through the leaks, but it will also pull it in through the supply duct, even without the help of the fan (the problem is smaller here because it will be heated on the exchanger).

This is where the possibility of using a mat or heating cable comes in (we do not control the shutdown of the fan), but only check the temperature (of just what?) and switch on the mat.

It would be a good idea to place a temperature sensor inside the exchanger (I think), in the cold air passage, and with it check what is the "condition" of this part of the exchanger. When its (the material? the flowing air?) is close to zero, we switch on the heating mat and now the question is what - the exchanger? the pipe supplying the air from outside? or maybe the chamber before the exchanger?

kurdebele666 wrote:

1. These heating mats are as a pre-heater? It makes sense, but eats up energy. The recuperator should defrost the exchanger 'by itself', using the used and heated air from the house - I guess that's more economical?

Heaters are of the order of 20-200W at times running 5- 10 minutes / hour ie 240 minutes / day .

Running a 200-300m3/h fan for 15 minutes is 20-75 m3 . According to the colleague, how much energy is needed to reheat the air?

You need to recalculate the simulation of operation.

As far as our latitude is concerned, in autumn and winter, the system with the hygrometer will be more out of order than in operation, and the recuperator will then only be an unnecessary component consuming additional energy , altogether taking energy out of the room for its own heating.

The interior of the recuperator itself is heated - the design must be suitable - allowing the heating elements to be positioned right on the surface subject to frosting (i.e. the interior surfaces of the duct 'lamellas').
In professional constructions, in the case of significant differences in temperature and air humidity, several stages of recovery, or rather, gradual heating of the incoming air, are used. This allows optimum energy recovery while saving energy wasted on process handling.

aaanteka wrote:

Heaters are of the order of 20-200W at times running 5- 10 minutes / hour or 240 minutes / day .

Running a 200-300m3/h fan for 15 minutes is 20-75 m3 . According to the colleague, how much energy is needed to reheat the air?

You need to recalculate the operating simulation.

I have no clue. Which heaters take 20-200W? Because I have seen a preheater minimum of 600W.

aaanteka wrote:

Which for our latitude , then in autumn and winter the system with the hygrometer will more fail than work , and the recuperator will then be just an unnecessary component taking extra energy , altogether taking energy out of the room for its own heating.

I think we have misunderstood each other. The recuperator will not be running because it will be off - it will not be drawing energy. The humidity sensor will be placed in the room, when it detects an increase in humidity it will turn on the ventilation until the humidity returns to normal. Why should the recuperator even work if the air is OK?

There will be two power sources on the switch, one of them will be connected to a radio socket with a remote control and when you want to ventilate the flat because: a party, bigger cooking, I let out a fart, you can use the remote control to turn the recuperator on.

I would like to stress again - I do not want to ventilate the house for the sake of ventilating, ventilation has a PURPOSE: to exchange used air, and used air is the air which has 1. excess humidity 2. excess co2. As I've written before, I'm assuming that I can equate co2 levels to the percentage of moisture in the air - because I'm assuming, perhaps incorrectly, that we release more water than co2 when we breathe, so when the moisture rises to sub-optimal levels, it's probably time to replace the air in terms of co2 too.

There is no point in ventilating the house for the sake of the idea.