Centrifugal fan with external knob for humidistat

I need to replace a Ventaxia Solo Plus HT centrifugal fan with overrun timer and humidistat. It's only about 3 years old but the fan started pinging against the casing and has now jammed. Also the cover clips were of poor-quality plastic that only reengaged about 10 times before one of them gave up. I'm therefore not keen on buying another the same.

The humidistat settings need adjusting quite often and in particular are very different in summer and winter. The fan is awkwardly positioned for access (on the ceiling directly above the bath/shower) and opening it to mess inside with a screwdriver is a real pain, involving fetching ladders and twisting my neck to get at the internal screws. I'd really to find a replacement with an external knob to control the humidistat without needing to open the case. I've looked around on the Web but haven't found one that's available in the UK. Any ideas? [I've seen axial fans with external knobs, but not centrifugal ones, and this has a

2-metre run of low-profile ducting beneathe the floo above so really needs to be centrifugal].

Thanks!

Reply to
openwater
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Why not set the existing fan so that it would run continuously. The add an external standalone humidistat in its power feed?

Reply to
John Rumm

We are about to install a similar system - but with an external humidistat and an external run-on timer which are in the bathroom so that the settings can be adjusted at any time. The humidistat also has an over-ride switch so you can turn the fan on whenever you want. Bits by S&P and sourced from TLC.

Reply to
David WE Roberts

Many thanks for the replies!

I find that in summer (when the bothroom radiator is off), the relative humidity needs to be set quite high or the fan is on continuously. In winter, with the heating on, the setting needs to be quite low to get it to come one at all, even when the room feels very humid and there is still condensation on the walls. It's possible that the radiator causes a warm pocket just below the ceiling where the fan is located.

A system with separate humidistat and overrun timer seemed quite attractive, but an electronic humidistat unit seems to be about £80 and a run-on timer with inputs for both the humidistat and the light switch is about £60 (that's from the just-fans site), even before I buy the fan. It's also going to be hard to get under the floor above (where there's a shower-room and the boads are hard to lift) to put wiring in new places. By contrast I can get a fan with timer and humidistat even from Vent-Axia or Xpelair for under £100 - but unfortunately I can't find one with the humidistat control external!

Reply to
openwater

Reply to
Perry525

Is there a good reason to buy a separate sensor rather than use the money for a good integrated fan/sensor?

Reply to
metric_trade

I understand all that, but you actually have my problem the wrong way around. Near the ceiling, where the fan/sensor is, my bathroom is actually much _warmer_ in winter than in summer. That is why in winter I need to set the humidistat to a much lower relative humidity in order to get it to come on at all.

Unfortunately there is no w>

Reply to
openwater

I think you may be missing the thrust of what I was suggesting, Keep the existing fan, set it to its most sensitive.

Now connect it to something like:

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will then do timer and external humidistat with a control where it is easy to reach.

Reply to
John Rumm

a good integrated fan/sensor?

Yes.

The integrated sensor will need adjustment (as will the external) from time to time as the seasons change. Its much easier to do this when its at a convenient level and does not require access to the inner workings of the fan while clambering about at height.

Reply to
John Rumm

Thanks. I stayed in a property that had a Manrose fan with integrated senso= r. It seemed to work as expected i.e. when the shower was on and for a whil= e after. But I didn't stay there for multiple seasons. Maybe I was lucky th= at it was calibrated correctly for that time of year.

I have seen one complaint about an integrated sensor detecting outside air.= Cheaper fans don't seem to have a means of blocking reverse airflow but ot= hers have flaps. Perhaps that helps reduce sensor false alarms.

I'm almost convinced to buy a separate sensor. But I'm puzzled as to why i= ntegrated units are so popular if they're bad. Is it that they're not that = bad, just slightly worse?

Reply to
metric_trade

Much depends on where you install it. If its easy enough to reach up and twiddle its knob then its not much of an issue. I had one like that on the wall in the bathroom of my last place. It was fine and since I could reach the ceiling in any room without difficulty from the floor, changing the setting was easy. If I mounted one the same way here, I would need a ladder to get to it each time.

Reply to
John Rumm

Hi John.

Many thanks. That does look quite an appealing solution and is certainly much cheaper than buying the electronic humidistat and overrun timer separately. I can't see from the description whether the Manrose unit you linked to is an overrun timer, or runs for a time from when a button is pressed, or from when the humidistat decides it is dry enough?

I can't actually keep the current fan as its case now seems to have warped enough that the blades can't rotate any more. But that's a detail.

John Rumm;2943892 Wrote:

Reply to
openwater

If I could find an integrated centrifugal fan with an external knob to twiddle then I'd be happy. It's opening the case to dig inside with a screwdriver while perched on a ladder over the bath that is tricky. External knobs seem quite common on axial fans (which are OK mounted on an external wall) but nonexistent on centrifugal fans (which are needed for longer duct runs).

John Rumm;2944095 Wrote:

Reply to
openwater

Can you give a link to an example? An external knob on the fan itself might suit me. My fan is in a low ceiling which I can reach without a ladder.

Secondly, I've just been looking at flow rate and ignoring the technology (axial, centrifugal). Is there a reason I should care about the technology if it can achieve the flow rate?

Reply to
metric_trade

Hmm. I'm afraid I was basing that on the fact that I have two different Manrose axial fans with external knobs for their humidistats, but they are quite a few years old so are probably not current models.

metric snipped-for-privacy@yahoo.com;2944964 Wrote:

An axial fan can deliver its quoted flow rate only when there is very little resistance (e.g when wall-mounted and all it has to do it push the air to a vent on the other side of the wall).

For longer ducting runs or for low-profile ducting, you really need a centrifugal fan to overcome the resistance.

Reply to
openwater

Would it be like the third picture down at:

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comments noted.

Reply to
metric_trade

Neither of the ones I have is identical to that. One is a 150mm one with a knob on the bottom very like the picture in the link, and the other is a 100mm that on checking has a screw on the front (not the bottom) rather than a knob.

Reply to
openwater

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