Johnward & VicVapour

[Dan Robinson]

The house has a heatloss of 37kW.

Nothing has been added for hot water.

Towel rails are with the hot water.

Hot water cylinder has a 38kW coil.


Happy days.

 

[RF Lighting]

I've wired loads of proper (wet) under floor heating systems, and they are the best way to heat a house, and I beleive the most economical too due to the much lower running temperature..

I would think it's only really viable to install it on a new build property so you can get the correct amount of insulation in under the concrete slab, but when it's done right, it's unbeatable.

The other type of UFH where you roll out a little mat under you laminate floor is completely different, and nothing more than a waste of time and money.

 

[ban-all-sheds]

Guess you've never seen a proper UFH system then?

If by "proper" you mean one which somehow magics its way out of the thermal store and hysteresis characteristics of floors, no, I haven't.

 

[ban-all-sheds]

The house has a heatloss of 37kW.

Outrageous.

 

[ban-all-sheds]

I've wired loads of proper (wet) under floor heating systems, and they are the best way to heat a house, and I beleive the most economical too due to the much lower running temperature..

And in the example above, what would the temperature of the floors be if you needed them to deliver 37kW?

And what if you want, shock horror, carpeted floors?

Or wood? Or do you plan to add to the barminess by effectively lagging your radiators with something with a pretty respectable U-value?

The other type of UFH where you roll out a little mat under you laminate floor is completely different, and nothing more than a waste of time and money.

The type of energy source is irrelevant. Stone flooring takes too long to heat up and too long to cool down, and any other sort of flooring is mad.

 

[Dan Robinson]

Outrageous.

Why?

 

[bernardgreen]

Hot water cylinder has a 38kW coil.

Which means nothing without information about the temperature differences between
[1] water in tank and coil ( average of entry and exit temperatures )
[2] entry and exit temperatures of the water flowing through the coil

Is it transferring any heat if the tank water is the same temperature as the water passing through the coil. ?

And if the effects of convection currents in the tank are taken into account then the Kwatt "value" of the coil becomes even more difficult to quantify.

 

[SimonH2]

The type of energy source is irrelevant. Stone flooring takes too long to heat up and too long to cool down, and any other sort of flooring is mad.

Ahh, you've experienced a typically badly setup system then UFH got a really bad rep back in the 70s and 80s (IIRC, I recall one of my grandmothers had it in her flat). This was typically electric, and got a really bad reputation because people tried to use it badly.

2 ways :
1) They'd try and use off-peak lecky and the floor slab as a store. So you get cooked feet in the morning and it's gone cold by the evening when you want it.
2) You'd turn it on only "when needed" - leading to the observation you've noticed, that large slabs do take time to warm up and cool down.

But the latter also applies to a system with radiators. If you let the house go cold, it takes a long time to heat up the building again. Yes, some of the air gets warm very quickly, but the building takes a lot longer (and in the meantime, your feet are cold).

My brother has put UFH in his cottage renovation. I have to say, his place is more comfortable than ours - I generally find the issue to be cold feet which is a design feature of "traditional" heating methods. Yes, extra socks etc are one answer - but then the reductio ad absurdum to that is we don't need any heating at all since we could just wear more/thicker clothes all the time (which is of course what used to happen a lot before central heating etc).

You do need to setup the system right, and also think ahead - ie not get used to making big changes to the stat and expecting instant results. But it's a darn sight better than the utterly c**p night storage heaters we have in the office at work where you need a crystal ball to work out what heat you'll need tomorrow to set the input control today

 

[bernardgreen]

UFH got a really bad rep back in the 70s and 80s

Because as you say it was little more than an out of site night storage radiator.

My brother has put UFH in his cottage renovation. I have to say, his place is more comfortable than ours - I generally find the issue to be cold feet which is a design feature of "traditional" heating methods.

I have yet to find a UFH system which has a comfortable floor temperature while still heating the room from chilled to a comfortable air temperature. Only when the room is kept at a constant temperature can the floor be comfortable to walk on in bare feet. Having to add thermal insulation socks to prevent feet being cooked is worse than wearing thick socks on a cold floor.

A mixture of systems is (in my opinion ) a good idea, rads or low temperature UFH for keeping the room warm after water to forced air heaters have rapidly brought the room up to temperature.

You do need to setup the system right, and also think ahead

The best idea is to live in the property for a while and from experience work out what is really needed and not work from tables of expected results of heat loss (house) and heat ouput (heating system components) But in todays world there is no time for that. The system has to be installed and working perfectly with the minimum delay. For me I am happy to spend a year to get the system in this cottage working in the way the cottage needs it to work.

 

[Dan Robinson]

Which means nothing without information about the temperature differences between
[1] water in tank and coil ( average of entry and exit temperatures )
[2] entry and exit temperatures of the water flowing through the coil

Is it transferring any heat if the tank water is the same temperature as the water passing through the coil. ?

And if the effects of convection currents in the tank are taken into account then the Kwatt "value" of the coil becomes even more difficult to quantify.

The same can be said of any cylinder. This cylinder has a coil rated by the manufacture at 38kW.

As with all coils, as the tank heats, the efficiency goes down, and is why I have a thermal store at home. But that is for another topic.

The boiler will go down to 6.8kW which is context of the house is pretty low.

 

[RF Lighting]

It's strange how the people who install and have actually seen how well the systems work all like UFH, and those who haven't think they are useless

 

[SimonH2]

It's strange how the people who install and have actually seen how well the systems work all like UFH, and those who haven't think they are useless

Try recommending a thermal store over in the plumbing section - this discussion is quiet agreement by comparison

 

[Dan Robinson]

True...

 

[ban-all-sheds]

It's strange how the people who install and have actually seen how well the systems work all like UFH, and those who haven't think they are useless

I have experienced them.

And I know others who have.

None of us have a good word to say for them, because of hideous hysteresis, and the fact than unless you have stone floors you are applying thermal insulation to your radiators, which is an utterly mental thing to do.

 

[bernardgreen]

It's strange how the people who install and have actually seen how well the systems work all like UFH, and those who haven't think they are useless

But is the installer the person who has to live all year round, summer and winter, with the system that works well on the day of installation in that it does what it says on the boxes.

A Rolls Royce works very well but is hardly the best vehicle for a rally driver to use for off road rallying.