Power washer exhaust

[bigdry]

Hi all has anyone here ever installed permantly a large diesel heater pressure washer such as a karcher HDS in their garage. I have one and wish to duct the exhaust from the diesel heater part outside the garage. I bought the suitable exhaust adaptor of ebay which takes the oval exhaust shape to a 200mm round form.

New Exhaust Fumes Outlet 200mm Chimney Funnel for Karcher HDS Pressure Washer 5902553710274 | eBay

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www.ebay.co.uk

Now need a cheap way to get this to flow the exhaust outside the building. 200mm flexible stainless pipe is expensive and unwieldy..,
Is stove pipe the only answer (probably reduced a bit to 6" diameter i reckon)?

cheers

 

[Barking Mat]

I'd be wary of reducing the diameter.

Advice I got from a company regarding a similar exercise for a genny, was always increase the diameter by 25%.

 

[knighty]

use galvanised duct, turn it 90' and come right out of the wall so you only need a shot bit?

 

[carbon]

With the machines I sell its usually 200mm that the adapters are made in. I usually use single wall stainless rigid flue but some of my customers have single wall spiral wound galvanized but do expect the section near the exhaust to rust after a time. Some that have hot machines mounted inside vehicles just use a short length of flexible stainless to guide the exhaust outside the vehicle when the rear doors are open. I have some machines mounted inside a 20ft container and the flues exit through the top and these are the same size as the exhaust on the machine but are probably only a 1.2m in length and they haven't had any issues in last 4 years. It depends on how long the exhaust has to be

 

[Turbo]

To get enough draw you might have to extend the ducting to above roof level, otherwise the boiler will soot up & the fumes might go inside the building.

 

[knighty]

there's a fan forcing air into the boiler, no draw needed (just no restriction either)

 

[Bullet2012]

As the exhaust from these type of machines has a very low flow , it will require a means to extract the fumes.
Especially as you will be reducing the exhaust pipe area quite considerably.

 

[knighty]

mine have always had good flow from exhaust?

 

[carbon]

The fan is there for combustion to get the correct air/fuel ratio. Adding more exhaust than the original can and will affect this ratio. I’ve found no issues with just over a meter but add over that in fixed installations and the exhaust does need to be above the roof ridge line to add with exhaust removal

I started repairing a machine at one site and the exhaust only extended as high as the eaves of the building and fumes from the exhaust were entering the building, extending it above the ridge has now stopped this issue

 

[knighty]

can you adjust the airflow into the machine to compensate for back pressure?

ones I've had have had dampers on the air inlet into the fan

 

[carbon]

Adjusting the air flow affects the air/fuel ratio and how efficiently the burner operates, which can then cause problems with the boiler sooting and needing more maintenance than it should. Once sooting starts this then changes the air flow through the boiler and makes the situation worse.

 

[knighty]

I meant adjusting the baffle to compensate for the extra flue resistance - opening the baffle a bit to keep the airflow the same?

 

[Turbo]

I meant adjusting the baffle to compensate for the extra flue resistance - opening the baffle a bit to keep the airflow the same?

Doesn't work, as carbon says. The blower fan is designed to push enough air through the boiler to match the amount of fuel injected in, with a bit of adjustment to fine tune combustion. It will not overcome a vertical column of air contained in a chimney, hence needing a draw in the chimney.

I used to install Karcher in plant systems & several times we had rows with customers putting in the wrong chimneys, either too small a diameter or not going past the roof line. They usually put in something you would use for a central heating boiler!

It got to the stage either they installed the chimney to our spec or we installed it ouselves, otherwise we refused to install the system. The usual spec was 6 or 8" selkirk s/s, twin wall preferred.