Which type of heating to choose? - experience / opinion

[ChrisMorgan]

Hi,

I am in the process of renovating a house and will be replacing the heating system (existing condensing boiler will remain as is new).

I have looked at various heating options namely conventional radiators, unfloor heating and skirtking board heating.

After doing some research I have ruled out radiators and considering underfloor heating or skirting board heating.

Does anyone have an opinion on these two options?

The majority of the house will be wooden floors, with the exception of tiles in the bathroom and laundry.

Regards,
Chris

 

[Alfredo]

Of the two i'd go for underfloor as it will give a more even heat. I've never been impressed with skirting heaters, though most of the installations I know of are quite old.

Where underfloor really scores is that it operates on a lower flow temperature, and depending on what make of condensing boiler you have (mines an old non modulating one..most modern ones modulate), the aim is to maintian a flow temp in 50-55c range as this will keep the boiler operating in condensing mode..i.e. the most efficient..for the maximum time possible.

I'd also investigate if its possible to fit an external weather compensation device to your boiler. This saves you money AND gives you better comfort as it brings the boiler in earlier and runs your system at an average lower temp, this avoiding the hot/cold effect of a conventional room stat kicking in and out.


Just a couple of thoughts for you.

Alfredo

 

[ianniann]

Agreed. Choose UFH over skirting radiators every time if you can manage the initial installation cost and disruption.

However, weather compensation does not do what is described here. What it does is add an extra layer of refinement to standard modulating controllers that taper down the heat being supplied as the room approaches the desired temperature. It achieves this by adjusting the "aggressiveness" of the heating map based on the external temperature. To some extent this behaviour must be learned since the heat loss at a given external temperature depends on the size of the house and level of insulation. Non-weather compensating controls may do the same type of learning, but without the external temperature they may not have as much information to base their predictions on.

People often confuse the idea of weather compensation with modulating controllers, but the two are different beasts. In theory you could have either one independent of the other, but in practice weather compensating controllers always (?) modulate the boiler flow temperature. You can certainly have controls to automatically modulate the flow temperature, assuming your boiler supports them, without weather compensation.

 

[Alfredo]

I confess to not being that 'with it' on weather compensation, so i bow to your expertise in the matter, but i did 'lift' my comment from the Viessman brochure on the subject, but obviously I need to delve deeper. I still think it should work well in combination with a condensing boiler and underfloor as long as the system is set up properly.

In principle though I am correct in saying that a weather compensating system will enable a condensing boiler to operate longer in condensing mode as it will help the boiler to operate at a lower flow temperature, and should be more economical as a result.

They do refer to Standard Weather Compensation with a fixed heating curve and Advanced Weather compensation, the latter being able to fine tune the heating curve to the building's construction/heat loss profile.

Alfredo

 

[ChrisMorgan]

Thanks to both of your replies.

Just to ensure we are talking about the same product, the one I had been looking at was this one : http://www.discreteheat.co.uk/

Is this what you were both referring to, when you said Skirt Rads?

Chris

 

[Alfredo]

I'm certainly not going to knock a product of which I have not been previously aware, and which seems to take Skirting heating to a different place, I'd just advise you to do as much research on it as possible, and if practical see a working installation.

I can certainly see the attractions though, and I'l have a better look at it later. My guess is it will suit a well insulated property, but sitting here in my Yorkshire Dales 1885 solid stone walled heat sieve, I doubt they could keep up, but aesthetically getting rid of radiators would suit this Victorian house well, so thank for flagging this up.

Alfredo

 

[ianniann]

Is this what you were both referring to, when you said Skirt Rads?

Well there's a whole lot of marketing gobbledygook on the web page, but they're still basically thin low-level radiators and I can't see anything that would avoid the inherent problems of such a system. They try to compare their product to UFH, but it lacks the one thing that makes UFH attractive which is the very low temperature heat supply provided over a very wide area (ie. the whole floor). Obviously they are much easier to fit initially and to maintain in the event of a pipework problem, and quite possibly cheaper as a result, but they will cost more to run and won't heat as effectively especially in large rooms (the same can be said of conventional radiators of course).

I confess to not being that 'with it' on weather compensation, so i bow to your expertise in the matter

Not me. I have very limited knowledge about weather compensation and at the same time very great scepticism. In part this is because the sellers of the technology make misleading claims and use terminology deliberately styled to confuse us. There is no theoretical reason why everything that is done by the most advanced weather compensation device cannot be done without an external thermometer. All the mutterings about fine tuning to the building heat loss profile just shows what is wrong with the entire concept. The only thing that matters to your heating system is the speed at which it is currently heating up (or cooling) down with a given heating input. Then the heat supply (ie the flow temperature) can be adjusted higher or lower as provided by the heating map. Attempting to calculate this information from a learned profile and the current external temperature is a profoundly stupid way of doing it that can never work properly simply because it doesn't include all the necessary information. As a result, weather compensation devices will always have to make assumptions and compromises which will limit their effectiveness. This may make such minuscule differences to the end result that you don't care, but then the whole step up from a straightforward modulating controller to full weather compensation only offers small potential gains in a domestic situation anyway.

As an example, I offer a quote from Veissman: "The only way to improve the efficiency of a good quality condensing boiler is to add weather compensation controls." What fishfood!

Also I will continue to interrupt whenever the pushers of "weather compensation" use the term when they actually just mean modulation of the flow temperature (sometimes called load compensation), whether based solely on the internal controller or with additional input from an external thermometer, because that's how anal I am

 

[Alfredo]

I'm very interested in what you say as my only personal experience of weather compensation systems are ones I came across in warden controlled housing schemes with a central boiler house and commercial boilers. They didn't seem to prevent the poor old residents from either freezing or frying, and seeing as I was only there to unstick/change a pump or something equally mundane, I never got the chance to understand precisely how they were supposed to work, but all the installations in all the units I worked on had weather compensation systems installed by electrical engineers with clocks/ programmers/ sensors and so forth.

It would have been nice to quiz whoever designed/ installed the kit as to precisely how it was all supposed to work.

Alfredo

 

[mickyg]

that thermaskirt looks horendous imo. Notice they only show straight sections on the website not the corners, or the joints not to mention the trvs in kicking territory.
UFH is far better if you can do it. Wouldn't worry to much about WC so much with UFH all over but it can be done but potentially problematic. If you have ufh all round and boiler set correctly it well condense all the time anyway.

edit, looks like they have got some "joint" photos now. dunno how they managed to get it looking that good! must have some amzingly straight walls.

 

[Happyplumber]

Its amazing what you can do with photoshop Micky,that and brand new dry lined walls.Not exactly the average house in the UK

 

[ChrisMorgan]

A big thanks to everyone that replied, this is very much appreciated.

OK so now I have been convinced to go with UFH, are there any special considerations I need to give, when choosing the wooden flooring? ON one website I found, it mentioned wooden flooring which has a metal back to it, so that the heat is distributed more evenly and acts as a heat sink.

Also I came across something called a metal diffussion plate ... is this a must with wooden floors?

Just to confirm, the UFH type will be pipes and not the electric mat type.

Any thoughts / comments on this one?

Chris