Warm Air Vent Heating to Radiators

[pampers]

All you need do was buy another unit. They just drop in on the plenum where the old was. Uprate the grills/registers too. Many of these system are ripped out because of ignorance by plumbers. Plumbers do not understand these things - not their field.

No it wasnt it in my case .

it wasn't a recessed unit in a nice cubby hole it was free standing in kitchen tiny kitchen huge unit.
I wouldn't even consider putting warm air in that property ,just because it was there already didn't mean it was the right choice for that property,as well as the price for the replacement would not have been viable either.

4 rads and a boiler i had ripped out and kept in lock up was the right option though

warm air is a option ,can be a good option but thats all it is isnt right for everyone or every house.

 

[Doctor Drivel]

lol, I also like to imagine a world with no old WAU (saying that I imagine a world where everyone has a linea cos its the law)


I though WAU, even the new ones were still very inefficient? gas->output wise,

There are condensing units. J&S have a condensing box that fits on a conventional flue stack.

 

[Gasguru]

Before you even consider replacing the unit the ducts should be checked for adequate size and condition. Even a modern unit will be useless if the system layout is poor (which was often the case on older systems).

Often the insulation on the ductwork may be missing or inadequate and can't be replaced if its within studwork or concrete floors. On older systems the duct sealing tape was paper based and by now will have disintegrated. That means your warm air just gets blown out into the studwalls or heats the floor slab.

Be aware that even replacing smaller units in flats can involve considerable work. The last one I replaced took 4 days (1 day just to cut out the old unit!). The J&S units generally have the flue at the back whereas the older units the flue is off the front - this in itself can be a real headache. Once all the ductwork was resealed and had new insulation the system worked well though. System ET (Modairflow) makes a big difference.

Also be wary of warm air companies - corners are often cut - beleive me when I say they can't be swapped out in a day - loads of work required.

 

[simond]

Warm Air was, and remains one of the most effective, and efficient forms of space heating available.

The comments about dust are misguided, newer systems with varispeed fans, pulsing burners (they do not modulate, Dr D) tend to lower the air velocity.

Warm air systems do not create dust, the dust is already there. For those particularly sensitive to dust, an electrostatic filter can be fitted which removes particles as small as tobacco smoke.

Many public buildings and offices are heated by warm air. I don't recall anyone complaining about it while shopping in Tesco. Or working in the office.

I haven't seen a flue heat recovery unit attached to a WAU, Dr D. Are you thinking of their Reno branded condensing boilers with a Gas Saver attached?

The other day we fitted a J&S Economaire 90 (largish Warm Air modulating system with room sealed flueing) and a Vaillant 937 for hot water only. So the customer kept warm air (because they liked it) and had mains pressure HW.

They also had a route for heating their future loft extension via the Vaillant, but it is currently just used for HW.

 

[Doctor Drivel]

Warm Air was, and remains one of the most effective, and efficient forms of space heating available.

The comments about dust are misguided, newer systems with varispeed fans, pulsing burners (they do not modulate, Dr D) tend to lower the air velocity.

Warm air systems do not create dust, the dust is already there. For those particularly sensitive to dust, an electrostatic filter can be fitted which removes particles as small as tobacco smoke.

Many public buildings and offices are heated by warm air. I don't recall anyone complaining about it while shopping in Tesco. Or working in the office.

I haven't seen a flue heat recovery unit attached to a WAU, Dr D. Are you thinking of their Reno branded condensing boilers with a Gas Saver attached?

The other day we fitted a J&S Economaire 90 (largish Warm Air modulating system with room sealed flueing) and a Vaillant 937 for hot water only. So the customer kept warm air (because they liked it) and had mains pressure HW.

They also had a route for heating their future loft extension via the Vaillant, but it is currently just used for HW.

Yes forced air is brilliant. The heat up rate is fantastic. They do have modulating burners, mainly on US models.

A full vent and heat recovery twin duct forced air system beats most others by a mile. Gills and registers can be hidden I have seen the behind coving and beams. I have also seen warm air from a conservatory ducted into he system using solar gain.

Yes, the Vaillant combi can do rads as well or maybe Myson fan heaters or small air-handing unit.

Yes, the units do not create dist and the use of laminates away from carpets has made a difference in many homes - forced air or not.

In the USA they tend to have a forced air system and a separate integrated burner gas water heater. Some have high flow Rinnai multi-point water heaters. Condensing units are common, by Lennox, Trane, etc. I personally would look into using a boiler (combi or otherwise) and a copper coil in an air handling unit. A decent controller can keep the boiler flow down to minimum levels, that does not give draughts, promoting condensing efficiency.

J&S did an add on box for conventional flues that was a part of their heat recovery and vent system that integrated into a normal forced air system.

J&S also did some very small units that fitted under stairs and in lofts - not sure if they still do. I recall one of these in house in the loft doing only the upstairs with grill via the ceilings and another downstairs under eh stairs. Two separate systems with individual temp and time control.

Grills and registers can be auto closed too - control by a local room stat. Very easy to do. If I recall correctly I think you need a VAV system for that to get full benefit, although it will work on most modern system irrespective.

Forced air is probably the most common sort of heating: in offices, supermarkets, and even in your car.

For those wanting an overview of forced air dispelling the myths:
http://www.sbfaq.borpin.co.uk/dokuwiki/doku.php?id=sbfaq:heating:warm_air

For those who say the value of your house drops with forced air, have a vent and heat recovery unit fitted and call it Fresh Air Ventilation Heat Recovery, then it sells. Fresh air speaks for itself and heat recovery is eco. You always have fresh air run through the house, which keeps the house fresh. A great bonus as is the free cooling in the summer.

 

[stem]

I hated my WAU with a passion. OK many say the new ones are better, but I don't know if they've solved the following:

1. Warm air blown into bathroom, displaced the existing air. Where did this moist and erm.. stale air go? out of the bathroom door down the passage and back into the inlet duct of the system for re-distribution to all of the rest of the house. lovely!

2. Kitchen, as bathroom see above.

3. No zone control. Hot kitchen when cooking, thermostat in cool lounge kept the system running which pumped more hot air into the kitchen. OK I would sometimes manually close the kitchen grille, but then forget to open it again before I went to bed. It was impossible to get a comfortable temperature in every room. Lounge temp was OK'ish where the thermostat was, but other rooms that were too cold one day were too hot the next if the sun shone on them (How do you size the ductwork for that?). This was my biggest problem, unless new systems have some sort of themostatic control on each grille, similar to a TRV I would avoid it.

For example now with a radiator & TRV we keep our guest room 16 deg when unused and increase it to 20 deg when we have guests. Couldn't do that with an on/off grille, OK there was some very limited hit & miss manual adjustment of air flow but of course that took no account of room conditions.

4. Noise transfer. Voices, TV etc travelled thro the ducts from one room to another, especially in the bedrooms.

5. I thought the fan was noisy, and maybe the new ones are better, but it doesn't take much to disturb sleep first thing in the morning when everything else is quiet. Just the airflow passing the grilles made a hiss.

6. Mine melted a visitors pair of new boots (well the sole came off) which were left on the floor at the side of a outlet. Not heard of that happening with a radiator.

US systems are generally different. Those I have seen have a furnace located in a basement and the heat rises naturally up the ductwork. They keep their heating on 24/7 so that actual heat emitted is constant and low.

 

[ollski]

I'm sure it's fantastic but I don't have it and never have. I do know that during the late 1990's the area I live was the fastest housing development in Europe and 50% were fitted with wau so I am not inexperienced with them and of those I would say 20% dislike it enough to consider fitting a complete wet system, that is my experience anyway.
I do wonder how blowing air around a house can not put dust into the air?, if it didn't there would be no point putting a dust filter in would there?

 

[Doctor Drivel]

and a Vaillant 937 for hot water only. So the customer kept warm air (because they liked it

The 937 is expensive and only gives 15.2 litre/min flowrate. The integral tank prevents the combi lag. The W-B 42 kW is about the same price, yet delivers 17 litres/min. Probably a better option than the 937

I'm sure the W-B can be a water heater only too.