Hot water & heating for campsite question

[afishcallededdie]

We have a small camping & touring site and are refurbishing a shower block to provide 10 individual 'wet rooms', each with a shower, basin and WC. We also plan to have underfloor heating. Our problem is how to provide adequate hot water at peak times, and provide energy for the underfloor heating, and tick all the right renewable boxes to fit in with our status as a David Bellamy Gold Award holiday park. Our primary fossil fuel is LPG, we only have a limited availability of electricity but we do have piped LPG from bulk tanks.

Here's what I've figured out so far:

1. 10 showers at 10L/minute, 5 minutes per shower with a 10 minute break between showers (for using the WC, shaving, drying, etc) means 20 minutes hot water per hour per shower. So 2000L per hour of water is required. This could be reduced by aerating the water, reducing the flow rate, and blending (if we had a stored solution). Still, we would need >1000L per hour at peak load.

2. An instantaneous solution could provide enough hot water for the showers/basins without wasting energy storing hot water which might not be used. However it could not make use of renewables and we would require a separate solution for the underfloor heating.

3. A stored hot water solution with say 1000-1200L capacity could provide enough hot water as long as the recovery rate was <1 hour and could also feed the underfloor heating. We would still have problems with introducing renewables unless we had additional coils in the cylinders, but these would reduce the recovery rate - the renewable source would typically use the lower coil and although we could produce enough hot water for the first showers of the day (heat pump) or the first evening shower (using solar), only a fossil fuel could provide recovery in an hour and this would only heat the upper part of the cylinder.

4. A thermal store would allow multiple heat sources including renewables, but would have to be very large to provide the kind of recovery rate we need. And I don't really know enough about them.

Does anyone have any different ideas or comments on the above?

Grateful for any ideas

Cheers

James

[electroline]

Fine so far, but now consider how hot you want the water and how hot is it when it reaches your premises, in the summer you might only need to add 20 deg C, I guess that in the winter you won't be needing much hot water at all, the water arrives at 1 or 2 deg C the chance of heating that using sunlight is zero, you could install a wind turbine.

You mention solar panels, LPG heaters and ground source heat pumps, I suspect that if you now work out the likely heat output versus cost for those you will find that the solar panels are the cheapest, then the LPG and the heat pump comes last, but it all depends how far south you are. Don't forget electric heating, there is negligible capital cost and it is really fast.

The secret is in the way you control it, thermostat on your supply water, thermostat on your solar and heat pump storage tank and thermostat on the supply water to the cubicles and motorised valves set to close as the cheapest source is expired.

Just one additional tip, heat rises, so make sure your plumber positions all supply pipes above its motorised valve and make sure the pipes run down at least another 300 mm so that conduction doesn't cause confusion.

[build4]

Hi,
Have you done anything jet?
If not how long is your peak time is take and between peak times how many hours do you have?
I belive to store hot water is a good solution but is have to be enough to supply your peak times and than recover between them.

Regards

Build4

[afishcallededdie]

Hi folks

Thanks for your help with this

I have looked at many solutions from traditional to super-bleeding-edge-exotica (eg Oskar stratified thermal store which costs about 4x any other system but is fabulous technology).

I have pretty much decided on using an Andrews Maxxflo, and am in the process of making sure we get the size right. I think we will wind up with a 90/200 unit which is 90kw burner and 200L storage. This condensing unit is highly energy efficient (allegedly 109% net efficiency) and has a very rapid recovery rate. Basically it stores 200L but can recover at the rate of 1500L/hour. The reasons for going down this route are:

1. We are only storing 200L of hot water which means that when we are quiet we are not keeping thousands of litres hot for no purpose

2. We can send pre-heated water to the device which means we could add a separate thermal store, heated with solar, heat pump, whatever, and feed this to the boiler so that it only needs to bring the temperature up by a few degrees instead of from cold.

3. It is highly energy efficient and I like that.

It is not particularly cheap (about £6,500 ex VAT) but on the other hand the installation should be simple because it is a single unit so will save some labour there.

If anyone has any experience of these units I would be pleased to hear it.

Thanks

[old dog]

Hi
if its any help I have been installing ecocents for the last couple of years. these utilise an air source heat pump on top of an unvented cylinder. they only use 800 watts of electricity and heat recovery to work I am positive these would be more beneficial as they are extremly cheap to run.

[Heatweb]

This may be a bit late, but this link is an online tool designed to help design the exact system you are looking for...

http://www.heatweb.com/designer/designer.php

Heatweb are experts in providing bespoke multifuel heating systems for small businesses, households, councils and industry.

Hope this helps!

The Heatweb Team