Extractor fan installation - do humidistat fans work well?

elsmandino

Hi there.

I desperately need to fit an extractor fan in my bathroom - at the moment, we just keep opening the window, which is not really enough (we have started to get black mould, now that the weather has turned colder).

I was just wondering whether had any experience of getting one with a humidistat - i.e. do they work well?

Our bathroom has lots of natural light, so I cannot rely on one that is controlled by the light switch.

I am struggling, also, to find a decent one that has both a humidistat and a manual pull cord (for, ahem, unpleasant odours). However, I assume that when someone has just washed their hands, this shall set the humidistat to come on, anyway.

Emmia

I wouldn't buy a bathroom fan without a humidstat again - we have windowless bathrooms, and before replacing the fans with ones with humidstats we had a mould problem... since replacing them with humidstat ones , no mould problem. 

You'll find they come on randomly if the humidity goes over a certain level (including at 3am). Ours doesn't have a pull cord, and isn't activated by hand washing alone - but I can't say there is an odour problem here.

I think this is the one we have, I went for a higher extraction rate due to the lack of windows (but it is £154) there is a cheaper one with a lower rate (£99) on the screwfix site 

https://www.screwfix.com/p/vent-axia-479089-100mm-axial-bathroom-extractor-fan-with-humidistat-timer-white-240v/870gy#product_additional_details_container

jennifernil

We have these in all bathrooms......

https://www.xpelair.co.uk/product/c4tsr-simply-silent-extract-fan

Ours is operated by a pull cord as we did not want it coming on with the light, it has a built in timer so runs on for as long as we have set it for after being switched off.

It is also available with humidistat operation, but we decided against that as we did not want it running while actually showering......pulling out the (expensive) heat as well as the moisture, or coming on during the night.  

We have a well insulated and very dry house, and find that a 15-20 minute run on time easily  clears any condensation on the window or mirror, but if you do have a mould problem, a humidistat controlled model could well be a good plan. 

Shop around on line for the best price, prices can vary a lot.

Eldi_Dos

One of the most common improvements that council or housing associations make when upgrading blocks of flats is fitting humidistat controlled fans.These may run constant for a couple of weeks till humidity levels are brought down but once that is achieved the flats are a lot more liveable.

tacpot12

I had a humidistat controlled fan installed in a rental property to solve a mould problem. It worked quickly to clear the bathroom of moisture. It did make showering a bit colder as it sucked cold air into the bathroom from outside to make up for the air it was exhausting. 

Eldi_Dos

Normally it would just draw air in from the hall which would be at the ambient temperature.
The benefits of a fan outweigh the drawbacks.

elsmandino

Thanks very much, everyone - really appreciate your input.

Have been doing a bit more research on this and there is some suggestion that a manual override pull switch is worth it if possible - the premise being that you manually start the fan running before you turn on the shower as by the time the humidity touches the fan, it has already started to condense on walls.

It then carries on until the room is dry again.

I have found this, which seems to tick all the boxes:

Envirovent SIL100HTP12V Silent Extractor Fan with Humidistat & Pull Cord | Extractor Fan World

Mardle

Have a look at Vent Axia continuous ventilation extractors. We live in an end terrace house built in 1908 and have one in our downstairs wet room. The extractor runs very quietly until the humidistat boost kicks in. https://www.vent-axia.com/healthyhomes/simplesolution/extractfans

elsmandino

Eldi_Dos said:

One of the most common improvements that council or housing associations make when upgrading blocks of flats is fitting humidistat controlled fans.These may run constant for a couple of weeks till humidity levels are brought down but once that is achieved the flats are a lot more liveable.

I finally got round to having one of these installed:

Bathroom Extractor Fan + Humidistat Timer Silent Tornado ST100HT (extractorfanworld.co.uk)

and to be honest, I have had a few issues.

Even with the humidity level set to 90%, the fan seems to be running constantly.

I contacted the manufacturer, who said that the fan needs to adjust for 48 hours before settling down.

However, I ran the fan at its default humidity setting (60%) for three straight days and it never went off.

Bit worrying, however, that Eldi says that it can take a couple of weeks to bring things down - I have a really powerful dehumidifier in my house, so I am hoping that things will settle down well before that.

The worst thing about a constantly running fan is that it is sucking out all the warm air from the rest of the house.

I shall give things another couple of days but I cannot help but wonder whether a regular pull switch/overrun timer would have been the better choice.

desthemoaner

elsmandino said:

Eldi_Dos said:

One of the most common improvements that council or housing associations make when upgrading blocks of flats is fitting humidistat controlled fans.These may run constant for a couple of weeks till humidity levels are brought down but once that is achieved the flats are a lot more liveable.

I finally got round to having one of these installed:

Bathroom Extractor Fan + Humidistat Timer Silent Tornado ST100HT (extractorfanworld.co.uk)

and to be honest, I have had a few issues.

Even with the humidity level set to 90%, the fan seems to be running constantly.

I contacted the manufacturer, who said that the fan needs to adjust for 48 hours before settling down.

However, I ran the fan at its default humidity setting (60%) for three straight days and it never went off.

Bit worrying, however, that Eldi says that it can take a couple of weeks to bring things down - I have a really powerful dehumidifier in my house, so I am hoping that things will settle down well before that.

The worst thing about a constantly running fan is that it is sucking out all the warm air from the rest of the house.

I shall give things another couple of days but I cannot help but wonder whether a regular pull switch/overrun timer would have been the better choice.

They can be somewhat capricious. I fitted one in our previous bungalow: there was no fan in the bathroom when we moved in, and mould was forming on the ceiling. After fitting the humidistat fan we never saw any mould again, at least not in the bathroom. The problem seems to be that the humidistat sensor is stupidly sensitive. Sometimes, and rather than pulling the cord I'd just blow on the fan to start it up in a bathroom which was already full of steam, other times it would start up when the door was open to other rooms, obviously sensing higher humidity in those rooms than in the bathroom. After fiddling with the settings a couple of times and then changing the fan, only for the new fan to exhibit the same behaviour I gave up and let it do its own thing. To be honest it seemed to settle down, as your manufacturer has suggested, though this was a different brand, an Xpelair.

My wife also pointed out, as you have, that the fan was drawing warm air out of the house, so if it doesn't settle down then yes, change to a manually operated fan. 

Apodemus

elsmandino said:

Eldi_Dos said:

One of the most common improvements that council or housing associations make when upgrading blocks of flats is fitting humidistat controlled fans.These may run constant for a couple of weeks till humidity levels are brought down but once that is achieved the flats are a lot more liveable.

I finally got round to having one of these installed:

Bathroom Extractor Fan + Humidistat Timer Silent Tornado ST100HT (extractorfanworld.co.uk)

and to be honest, I have had a few issues.

Even with the humidity level set to 90%, the fan seems to be running constantly.

I contacted the manufacturer, who said that the fan needs to adjust for 48 hours before settling down.

However, I ran the fan at its default humidity setting (60%) for three straight days and it never went off.

Bit worrying, however, that Eldi says that it can take a couple of weeks to bring things down - I have a really powerful dehumidifier in my house, so I am hoping that things will settle down well before that.

The worst thing about a constantly running fan is that it is sucking out all the warm air from the rest of the house.

I shall give things another couple of days but I cannot help but wonder whether a regular pull switch/overrun timer would have been the better choice.  

I don't think my house has ever been as low as 60% RH, even when I was using a dehumidifier!

I wonder if you are just setting unrealistic expectations of how low you can get the household ambient RH?  If you are sucking air out of the house, it is getting replaced from somewhere and at this time of year that incoming air will almost certainly be in the 80-95%RH range - sure, that drops as the air is warmed inside, but achieving 60%RH can be a tall order in a lot of houses. 

If you set the fan to 80% does it shut off?  If not, then the humidistat is faulty.  If it does, then you perhaps need to alter your expectations and adjust the settings to get a balance between achievability and running time.