Room heating & Convector fan output (BTU etc)

In an attempt to get a warm shop this winter I discovered the Myson convector fans (utilising C/H water)

Anyway, using the Rad. Calc. from discountheating.co.uk establishes

13500 BTU to heat.

Question is, I have the choice between 2 models. one has a MAX output of 11081 on normal setting with a "boost" of 16628 whereas the bigger one has a normal setting of 15625 with a boost of 22331 BTU

Size isn't really an issue, main concern is, would the smaller heater need to run on "boost" setting full time to maintain temp or would I be better with the bigger unit running on "normal" with the option of much higher "boost" for the really cold days.

Shop is 9m x 5m with solid floor, in between 2 other shops (one empty) with solid brick walls. Ceiling is suspended at about 2.7M

Shop front is almost North facing, so when the wind blows its incredibly cold.

I'm favouring the bigger of the units so the fan can run at a lower speed for similar output. Once up to temp though, would the bigger fan be superflous to requirement rather than pottering along maintaining a temp.

TIA

Pete

Reply to
Pet
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Yes. Excellent things. I've got a kickspace in my kitchen and intend to install a Hi-line in my conservatory.

Firstly, always work in kW, BTUs are for those stuck in the 1970s!

Secondly, you want to be able to run on normal setting, as it is much quieter. The thermostat means that the effect of oversizing will just be to affect the mark/space ratio, making it off more than it would have been.

Basically, if you have no objection to the price or size of the larger model, buy that one!

They are incredibly effective at heating large areas cheaply. The kickspace transformed my cold uninviting kitchen into a cosy space, despite it being long a thin, which is very hard to heat by conventional radiators when you don't even have any available wallspace. The best thing is that the whole room heats up very quickly compared to radiators.

The only real downsides are increased cost and slight noise, which would preclude their use in most bedrooms. Also, they work best will a zone all to themselves. If this is not practical, use a 2 port valve connected to a room stat. It will only then function when the zone to which it is connected is running, but this is better than just connecting it up full time to the zone, as they tend to hog the flow.

Christian.

Reply to
Christian McArdle

Thanks for the advice Christian. Currently we only have 2 teeny radiators on the shop circuit which is seperated from the flat above the shop by 2 x motorised ports.

Stick a room stat to controll the shop zone (currently running from the HW program on the combi boiler in the flat, so there's not much competition for C/H water as we very rarely have both zones on at the same time.

I'd best get on and order the beasties from our local plumbers merchant as the're virtually the same price as from discountheating.co.uk give or take a couple of quid.

Finally, we have an extension off the back of the shop leading to stock room I am presuming I could set the shop and the extension up as 2 zones ( so 2 zones within a zone) with seperate room stats both of which could switch on the CH "shop zone" if either has demand and off when both are satisfied?

Note - Flat zone is of CH side of timer, Shop is on HW side, so room stat would connect in place of cylinder stat as all on a combi.

Thanks again for your time.

Reply to
Pet

Why 2 motorised ports? Or are you including the flat zone?

Correct, although you may prefer to disable (or even reuse) the "downstairs" zone valve and make it conventional S-Plan-Plus, as it will be more reliable and understandable to any servicing staff.

I'd rename the HW on the programmer with some sticky labels, or somone will get confused. I assume you don't have a hot water cylinder? If you do, then don't wire the downstairs to the programmer at all. Just wire them permanently on and use programmable room stats. You should probably use them anyway and just set the zone to always on.

Christian.

Reply to
Christian McArdle

=============== I found that the room cools down quite quickly once the fan stops blowing. There is virtually no residual heat such as you would get from a conventional panel radiator. You have to balance this rapid cool-down against the quicker warm-up.

You might be better off with a conventional radiator timed to come on before you need to use your shop.

Cic.

Reply to
Cicero

I don't find this. You might want to alter the position of the room stat to avoid any such effect. The room stat manages to keep the temperature within

1C of target, which is plenty good enough for me!

However, with poor room stat placement, it may not be responsive enough to keep an acceptably narrow temperature range in practice.

Christian.

Reply to
Christian McArdle

Indeed. one for flat and one for shop

Only real change then would be to include the 2 small radiators into shop zone(for simplicity of plumbing),T off before current shop zone valve with a new zone valve to loop through to extension zone then run programmable stats to controll new valves.

Pipe wise, I am presuming 15 mm F & R to both new heaters tapped off existing 22mm F & R from zone valves would be fine as heaters are 15mm in & out.

HW renamed already. Prog stats will make things a whole lot simpler.

Thanks agian for clearing my mind as to how to configure things Christian.

Cheers Pete

Reply to
Pet

Yes. There's no problem sharing the shop zone with radiators, provided that they heat the same room. Generally speaking, though, the fan convector is so effective, that the room stat will be satisfied so quickly that the radiators barely get warm. This is one reason why not to use more than one room per zone when using fan convectors. The other rooms would never heat up properly.

You might want to consider removing the radiators to save yourself valuable wall space. At least, consider turning them off over winter to see if you really need them.

IIRC, 15mm is good for about 6kW. If you exceed this, use 22mm.

Yes, but it is still worth keeping the programmer, even if it is mostly set to always on. It provides a central location to turn the heating off, rather than having to go round all the programmable stats. Also, if you have wayward teenagers with a subzoned room, you can prevent them sticking the heating on at 25C all night by timing it to go off! Obviously, the first requirement could be performed more cheaply by a switch, but if the programmer's already there...

Christian.

Reply to
Christian McArdle

Unfortunately, being a shop, wall and floor space is of a premium. To get the desired heat output required by pannel rads I would require at least 3 very large vertical panells (regular shape ones would dominate most of the walls)

Also, I am presuming placing the convestor can above both entrance & exit doors (through which the wind seems to make a direct line, we will also achieve a "warm air curtain" effect, reducing wind chill factor significantly.

We have managed in the past with about 4KW's of electric fan heaters and an IR calorgas heater for personal warmth.

Looking forward to warm fingers and cozy toes this winter.

:¬)

Reply to
Pet

Mostly you run the fans off an (external) thermostat. I'd get the big one and let it cycle away gently and quietly.

Reply to
The Natural Philosopher

Mmm. I have isolation valves to balance all mine - they are on a zone with some rads, and its really no big deal. Don't have valves to control em - just have room stats controlling the fans. Only downside is occasionally in the autumn and spring the water going through is enough to heat the room a bit too much even with the fan off.

Reply to
The Natural Philosopher

Surely room stats controlling the boiler/zone valves would eliminate the problem? From what I can make out, the fans have their own internal 'stat anyway.

Reply to
Pet

Yep, that's pretty much what I reckoned. Plus having the greater than required output for when "the north wind doth blow" that bloody icy chill that even blows the door open against it's auto-closer.

Reply to
Pet

Indeed. However, TNP seems to suggest that they aren't so bad even sharing a zone.

The internal thermostat is just to stop the fan running when the water is cold. It does not regulate room temperature, as required by the building regulations.

Christian.

Reply to
Christian McArdle

Thats merely to make sure they don;t come on before water temp is up to

80C, or is on mune.

yes, loads of motorised valves or an overall stat somewhere would eliminate the problem. But I can't be arsed.

Reply to
The Natural Philosopher

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