Navitron Renewable Energy and Sustainability Forum

HEAT PUMPS & Geothermal Energy => Heat Pumps => Topic started by: fp29 on December 28, 2010, 04:40:25 PM

Title: ashp to water
Post by: fp29 on December 28, 2010, 04:40:25 PM
A friend of mine runs a laundrette and has 8 gas driven tumble dryers all discharge to the out side air i have been saying to him for some time about a ASHP to recover waste heat and heat his water side on the washing machines also a heat recover on the lost hot water from the washers any ideas how this can be done

Title: Re: ashp to water
Post by: knighty on December 28, 2010, 05:36:39 PM
google for........ heat recovery ventilation systems

fit one of those to heat the inside air/building

then for hot water, use the exhaust of that to heat the water via an air source heat pump

what kind of water does he have already ? just a boiler or a tank too ?  gas or electric ?

if he is heating water via electric then it would be better to use the ASHP as much as possible (unless it's very cold outside - in which case only use it when the dryers are running), if he is heating via gas then I'm not sure if he will be any better off using the ASHP... even with the air input pre-heated by the dryers

if he just has a boiler, then I would personally fit a tank (headed by the heat pump) and have that feed into the boiler - that way he will still have hot water first thing in the morning before the dryers are run..... and once the ASHP has been running and the tank of water is hot, the boiler won't need to run (it will stop running automatically when the hot water going through it is hot enough)

Title: Re: ashp to water
Post by: qeipl on December 28, 2010, 09:49:01 PM
I use one of these in my house -
The ASHP takes warm air from the shower and utility rooms, transfers the energy from the air to the water tank, and exhausts cold air outside.
Much more efficient than a heat recovery ventilation system.

The system could work for a laundry but he'd have to think carefully about the design, for example:

The ASHP will stop running when the water in the tank is 55 deg (as the washers are probably always used before the dryers the water temp will probably be lower than 55 deg when the dryers are in use, so this may not be a problem).

If the dryers have their own extract fans they might have to be disabled when the ASHP is running, otherwise the ASHP might not work efficiently, or be damaged.

The ASHP may not process air quickly enough to match the output from the dryers.

What do other laundries do?