How much do these things cost each?
http://www.envirovent-specifier.com/heat-sava.php

Thanks Ed.

If it's a supply and extract how would you do a whole house? They say you put them in kitchens and bathrooms but wouldn't you need one for each habitable room? Either way it appears to be a very cheap way to ventilate with heat recovery. But I expect very noisy at night in a bedroom.

I had these on the short list to go into my bathroom, but they just don't seem to be worth the extra money over the alternatives like the Vent-Axia models. I went with an HR-25H in the end.

I really liked the look of the Heat-Sava (stupid name notwithstanding) and tried to find a reason to get one, but I just don't see why they cost so much more.

Seascape: the supply and extract air on these single room units is directed away from each other to a certain degree, but there must be a certain amount of mixing. However, they do work effectively. Mine manages to control humidity throughout my (otherwise leaky) house pretty well.

Depends what you're comparing to I guess. They're a quarter the cost of a decent wholehouse MVHR or PVHR system.

Yeah that's what wondered. Their webpage says "ideal for both refurbishment and new build installations."

If you rely on these systems to ventilate your house, and they recover heat, then why is the outcome any different to a whole-house MVHR or PVHR system?

Posted By: Shevek
If you rely on these systems to ventilate your house, and they recover heat, then why is the outcome any different to a whole-house MVHR or PVHR system?

You wouldn't rely on one as your primary source of ventilation, they just don't shift enough air.

Posted By: fostertomDon't think these operate on a 24/7, lo power, lo noise, trickle principle?

Yep, they do. The only real difference with the Heat Sava is that it's balanced, but IMO that's actually a negative for a single room HRV unit. Apparently it's quieter, but I've not actually heard one so I couldn't say. And I suspect every manufacturer will try and tell you theirs is the quietest.

I was quoted £350 installed (Justfans have them for sale for £285) - all plus VAT

Does anyone have thoughts about a PIV system with proper extractor fans as an alternative ventilation system?

Envirovent tell me they would be acceptable to Building Control (not yet tested though) without trickle ventilation as well, the system is cheap, there is minimal installation disruption and warm air on the landing will be moved around

Can't see any recent threads about PIV

You are all missing their USPs. Firstly, they have a steplessly increasing speed related to %RH hardwired in - this means no sudden huge increase in sound and no issues relating to setting the RH boost level twice each year - jolly good for social or rental housing too as the renters can't interfere with high humidity extraction when they put their washing on the rads :) Secondly, they have a summer bypass mode (only one other Single Rm HR unit has this I think). Thirdly, they can be fitted up to 600mm wide walls as they have 3 or 4 (can't remember) different sleeve lengths.

I don't understand discussions about using for whole house or not - look at the Air Change figures compare to volume of your house = answer. Of course better to have where you would normally have extract on whole house - ie high humidity rooms. It is going to be cheaper than retrofitting a whole House solution up to medium sized house at least and this will be the subject of my next discussion.

Same for noise. All single rm HR units are 20-24 dBs @ 3m. There is one HR Unit advertised for bedrooms (can't remember which one but is Vent Axia) but they stupidly didn't test its noise level on trickle - I am sure it is lower than 20db but only because it's sister unit has the same metrics except for air flow (ie uses same power for less air movement). 20-24dB is is unacceptable in a bedroom, or indeed lounge. It is possible to baffle (ie put in a box) and of course this would further improve efficiency as you would have to ensure segregation of in/out flowing air.

Watch out when buying as there are still some of the old modelS knocking about.

Posted By: Shevekaround a 1/3 price of the MVHR

Posted By: ShevekProblem as I see it is noise in bedrooms/living rooms.

Exactly where I am at too, though there is a single rm ducted unit from Vent Axia which could be a Godsent if your building construction plays ball. The bedroom one I mentioned might be OK for a lounge but with that price difference it has surely got to be worth some unique-to-location clever boxing in DIY job. Whatdoyouthink?

Good afternoon,

I am the product manager for the heatSava here at EnviroVent and wanted to address a couple of concerns earlier posters had.

We normally recommend fitting the heatSava Single Room Heat Recovery (SRHR) unit in kitchens and bathrooms. The unit can be fitted in bedrooms but this is not usually necessary. The unit operates at a background noise level of 22 decibels which is very quiet (even on boost, the heatSava operates with significantly less noise than other units on the market). The unit also has a ‘Night-time setback mode’ which reduces noisy nuisance running during the night.

Regarding the recirculation of stale air – both the internal and external vents have been spaced and sized so that differences in airflow direction and velocity are created, and these prevent any significant recirculation from occurring. We have carried out airflow simulations that confirm that recirculation does not occur to any noticeable degree.

The heatSava does cost more than some other products on the market, however there are numerous extra features & benefits that are unique to the heatSava:

• Most importantly the heatSava is fully balanced meaning the same amount air is extracted and inputted. Units which are not fully balanced may give efficiency ratings that are inaccurately high.
• The heatSava has a fully automatic Summer Bypass to prevent rooms from becoming too hot on warm days, and a Frost Protection system as standard for cold conditions.
• The heatSava constantly tracks humidity and automatically increases extraction rates to keep pace with the increased humidity. This requires no user intervention.
• The heatSava has a range of cell widths (100 and 150mm) and lengths (300, 430, 500, 600mm) which allows it to be easily retrofitted into a wide range of existing situations. The 100mm cell width is generally used in bathrooms whereas the 150mm cell is usually used in kitchens. Both units are available in low voltage versions.
• Some other units on the market may experience problems with condensation in the heat cell. The heatSava has been designed so any condensate drains harmlessly to the exterior of the property.
• The heatSava is exceptionally easy to maintain and clean unlike some other units which require the removal of the entire wall sleeve for cleaning.
• The heatSava is built in our own factory in Harrogate, North Yorkshire allowing us to maintain our rigorous quality standards.
• The heatSava has a renewable five year warranty and is part of our eco-friendly Lifetime Range.

I hope this answers some of the queries. If anyone has any further questions please post here or give us a ring on 01423 810810.

Thanks

Can this product be modified at all to fit my 680mm walls?

Can't running in summer also be used for CRV (coolth recovery ventilation)?

Bit of a concern regarding possible condensation in the inbound air path maybe leading to grow in the ducts. Is that what that HeatSava text is talking about?

Still, I expect to leave my MHRV running in the summer. In a well insulated house in the north of Scotland with smallish windows overheating is not likely to be a big problem anyway. Opening windows just invites in midges and other critters whereas the MHRV will be filtered.

It might be fine if you understand what you're doing but I wouldn't be handing that out as advice to any old home owner. In an airtight building the implications of turning off the background ventilation and then forgetting to open windows is not good. Even if it was my own place I'd leave them on because I wouldn't be able to trust everybody else living here to manually manage background ventilation.

Also, depending on where you live, security could be an issue. Ok to leave windows open when you are in, but at night and when you are out?