Recoheat

Andrea15

Has anyone ever heard of this gadget? It seems to be some sort of pump you install in the flue of your stove to get more hot air in the house.
I have just come across it by chance; after a search here nobody seems to have mentioned as yet.
As I am disappointed with the heat output of my stove, I am always trying to find ways to improve its output. 

QrizB

It looks to be a flue gas heat recovery system.

Based on the quoted airflow of 1 litre per second from their pump, I guess you might get an extra 2-300 watts of heat out of your stove (recovered from the flue). Is this going to make a big difference to the temperture of your room? Unlikely.

You'd acheve the same extra heating with a 250 watt heat lamp (example) which, if you ran it for eight hours a day, 100 days a year, would cost about £50 a year in electricity. You could use it for six years for the same cost as buying a Recoheat.

Netexporter

I just have a couple of thermo-electric fans on top of my wood-burner. I have them blowing across the flue pipe and they certainly speed the temperature rise in the room. They don't start turning until the stove top reaches a temperature of about 100 degrees C. I got the two for about £30 and they came with stove/flue thermometers so it is easy to keep the stove in the ideal combustion range.

Andrea15

I find the "self powered" fans totally useless, or at least the "self" bit, reason why I have it now battery operated. 

matelodave

Just had a shufti at this magical device  and TBH it smacks a bit of snake oil

1 - it needs the flue to be modified to fit it - probably not a DIY job for most people
2 - with the coil in the flue its going to make it impossible to sweep with a brush unless you do it from the top of the flue or find some way of removing the unit easily if you usually have the flue swept from below.
3 - not sure about an aquarium pump humming away gently with a length of plastic pipe hanging down the side of the stove.
4 - £299 is a lot of money to splash out on something that probably wont make much of a difference, despite what the bloke says in the video, plus you'd have to get the flue modified to fit it which could add quite a bit extra to the upfront cost.

FreeBear

matelodave said:

Just had a shufti at this magical device  and TBH it smacks a bit of snake oil

1 - it needs the flue to be modified to fit it - probably not a DIY job for most people
2 - with the coil in the flue its going to make it impossible to sweep with a brush unless you do it from the top of the flue or find some way of removing the unit easily if you usually have the flue swept from below.

I would disagree that it smacks of snake oil. I have seen similar designs using a coiled pipe inside the flue, but using water instead of air. Done right, it doesn't prevent the flue being swept from either end. An alternative (which I did consider briefly) is to wrap a coil of pipe around the outside of the flue. Clamped tightly, you'd still get a transfer of heat without the inconvenience of potentially blocking the path of a flue brush.

Fitting one to an inset stove is not an easy task (forget it as a retro-fit option), and gaining access should it need repair is not possible. On those grounds, I would suggest that it is not suitable for all stoves, contrary to the manufacturers claims.

matelodave

Try getting a flue brush up past this then - https://www.recoheat.co.uk/product-page/recoheat-airflow-heat-recovery-system-for-5-stove-flue

I wasn't actually suggesting that the concept was flawed (ie heat recovery from the flue) but the Recoheat thingy wodged into your flue and using an aquarium pump to blow air does look a bit like summat a DIY bodger would try and TBH doesn't really look worth anything like £300

lohr500

Andrea15 said:

I find the "self powered" fans totally useless, or at least the "self" bit, reason why I have it now battery operated. 

Our five or six year old cheapo Aldi self powered fan is still going strong. 
What was useless about the model/s you tried?

Andrea15

The thermocouple stopped working. I changed it, but after a while the new one stopped working as well (yes, the conductive paste is there as well). Now I have rigged out a battery pack to operate it. 

Netexporter

Andrea15 said:

The thermocouple stopped working. I changed it, but after a while the new one stopped working as well (yes, the conductive paste is there as well). Now I have rigged out a battery pack to operate it. 

Has the fan got a bi-metal strip in the base, which lifts it slightly off the stove top, when the temperature is too high for the battery?

Andrea15

It does have a metal strip, but I am not sure if/how it works.