Does rain affect thermal efficiency of motorhome bodywork?

[Moped]

We are having our first wet day in Spain since our arrival weeks ago (no doubt other forum members are too!) and for the first time since our arrival the temperature controlled heating has come on. We have had it set at 18 degrees C as the minimum and what with using gas to cook meals and boil the kettle this has kept the van warm enough overnight for the heating to be redundant up until now. The fact the gas boiler has come on suggests the van interior is now loosing heat through the bodywork at a faster rate than it has been. The only difference is the constant rain. The outside temperature is no different to the normal. It may of course be simply that the lack of sun due the the melamin coloured sky is not keeping the van warm during the day. But curious to find out if rain does indeed affect thermal efficiency of bodywork. I suppose the rain running down the side of the bodywork is drawing off heat and therefore the bodywork is cooler than it would otherwise be. Have I answered my own question? :idea:

For future planning and for heating gas consumption is it better to be in a cold dry environment at say 5 degrees C or a mildly warmer UK wet environment at say 10 degrees C. Which would require greater use of gas for heating? We are relative beginners at touring in cooler conditions having until recently been summer only tourists. I would prefer dry but cold rather than wet but warmer.

 

[st3v3]

You need to get out more lol.

In answer, you will get a cooling effect, but I suspect it's more to do with the lack of sun. And I'm surprised the outside air temp isn't a little cooler...

 

[landoboguy]

Id agree that you have probably answered your own question that the cooler rain is drawing down the temps slightly.
One things for sure, your warmer then here its taking a turn this week.

 

[Channa]

Don't forget motorhomes have ventilation for habitation and gas purposes and the humidity does play a part bearing that in mind

Heating and ventilation engineers consider something called "sensible heat" when designing systems best way of describing it is the heat that can be felt and humidity plays a part in that ( why air con systems shouldn't be overspecced) so the atmosphere in effect plays a part in how comfortable you feel not specifically the temperature.

The evaporative effect of water drying and its effect on what it contacts will also alter the environment

An interesting question

Channa

 

[colinm]

The evaporative effect of water drying and its effect on what it contacts will also alter the environment

Channa

As this, we live in a c1750 house with no damp course, in summer it's like living in a fridge due to the damp evaporating off the walls.

 

[colinm]

Similar dated and listed building for me too, with no DPC at purchase, I got wall drilled and injected with chems, inside horse hair plaster removed up to metre high, then coated with renovating plaster, this was approx 30 year ago, ni damp issues, can you not do same?

Due to the works which happened before we had the house and it's type of construction, it would need floors dug out and walls completely underpinned and DPC installed, not going to be done while we're in the house.

 

[Val54]

Are you referring to internal plaster, or chem injection, or both?

Terry,
If you want some background reading, this is a good a place to start as any .............
https://www.heritage-house.org/damp-and-condensation/managing-damp-in-old-buildings.html
Dave

 

[Compo]

damp course

do i need a damp course in my mh please?

 

[Val54]

do i need a damp course in my mh please?

Only if you have taken the wheels off and are using it as a static van

 

[Val54]

“This thread has got me hitting a few walls with damp metre, fortunately, readings are acceptable!”

That’s good to hear Terry, the moral of the story is that there is no one-size fits all solution when it comes to maintaining old buildings and lime mortar is great stuff when used properly. Like us, old buildings need to breathe Thanks for the link.
Dave

 

[st3v3]

A specialist damp proofing company,.not a specialist period building damp proofing company. Not your fault: you didn't know you need a specialist specialist.
Another link to look at: Damp Proofing Old Homes & Period Properties

Your link says to use chemical dpc and renovating plaster, two things you said not to use above. I'm confused....

 

[Borders2]

When semi sub drilling rigs are conducting flow tests of oil/gas wells they flare off (burn) the oil and gas. This can generate considerable amounts of heat as one might expect. As the flare booms are only some 100 ft long the heat is considerable on the metal surfaces closest to the flare.

To counter this sprays are set up and the fire pump is employed to pump considerable quantities of sea water over the surfaces being heated. This has a very effective cooling effect on the hot steel.

Sound familiar?

B2

 

[Channa]

Talk about tangents, from MH's to old bricks and lime mortar......hehehe.

Indeed Terry, I am planning my extension in wattle and daub as we speak :lol-049:

channa

 

[alcam]

Indeed Terry, I am planning my extension in wattle and daub as we speak :lol-049:

channa

You'll need lots of sheit

 

[st3v3]

It says not to,......….

Do:

Reduce external ground levels - the level of the garden or driveway may have been slowly raised over the years to the extent that it has bridged the DPC and need to be lowered
Balance insulation and ventilation – older properties were constructed in a way to allow them to breath. If your building is no longer able to breath as it once did you need to keep it well ventilated. Try opening windows across opposite sides of rooms to allow cross ventilation. The other issue is with insulation - with high fuel costs we are keen to use lots of insulation to keep heat locked in and reduce our energy bills. Unfortunately, by doing this, we hinder the required ventilation, which leads to condensation issues. Installing extractor fans, drimaster eco systems or heat recovery units will help increase much needed ventilation and reduce condensation.
Install extra air bricks to allow ventilation
Get a professional to carry out a chemical injection DPC or any other retrofitted DPC if required
Use lime-based plasters and renovating plasters rather than cement where possible

Bold was the bit I was referring to.

Avoid:

Incorrectly installed chemical DPCs and waterproof render – make sure you consult a professional before taking this course of action
Using impervious materials that can trap in moisture. Cement-based pointing and render for example can make damp problems worse. Cement pointing on the outside of your property can prevent a building ‘breathing’. Often with period properties you see the use of lime mortar, which is both porous and permeable. When this decays overtime, it is often replaced with a cement mortar that stops the building breathing.
Injecting DPCs into hard non-absorbent bricks or old engineering bricks.

So, as long as the outside of the building isn't cement render, and can breath, waterproof cement is commonly used on the lower inside without problems. Renovating plaster on the upper part of the wall also allows the inside to breathe.

PS - the section that begins "It’s unlikely that rising damp is an issue" refers to Victorian houses, the way I read it.

 

[Val54]

As we seem to be staying off topic......... )

“So, as long as the outside of the building isn't cement render, and can breath, waterproof cement is commonly used on the lower inside without problems. Renovating plaster on the upper part of the wall also allows the inside to breathe.”

I mentioned in a previous post that one size doesn’t fit all situations and I certainly wouldn’t endorse the quoted generalization without knowing the type of wall construction, it’s condition and the nature of the damp problems. Condensation and salting from long term damp can easily be made worse by using waterproof cement mixes internally without knowing the cause of the problem.

 

[st3v3]

Quite, no two are the same...