MVHR discussion..formerly 'negative thermostat'

[RogerS]

I'm not sure what you call such a thing but what I'm after is a thermostat that 'makes' the contact over a certain temperature. It's for controlling the heat circulation system that I've talked about.

Without the right term, I can't Google it.

 

[Mike Jordan]

I think it's called a "make on rise"thermostat. A trip to your local electrical supplier should sort your needs.
B &Q are not likely to be any help!
Mike.

 

[Tusses]

Don't they have 2 sets of contacts , like a relay ?
The last one I bought did

 

[Tusses]

very quick look at screwfix .. 2 of these have NC and NO contacts

http://www.free-instruction-manuals.com ... 457824.pdf

 

[RogerS]

Many thanks, everyone...looks like the T6360B will fit the bill.

Now if it was a 'smart' one I could use my phone to adjust it since it will be mounted up in the ceiling (most likely) :eusa-whistle:

 

[Robert]

Or you could use one of these -

https://www.amazon.co.uk/Inkbird-Temper ... B018K82UQU

More wiring to do yourself but these are the same but cheaper

https://www.amazon.co.uk/dp/B0185M6I28?psc=1

I have 2 of these controllers of a different brand but identical and they have been completely reliable and remember the settings when left disconnected all summer.
Better than a simple thermostat as you can set the hysteresis to control switching intervals.

not wifi though

 

[Mike G]

Roger, I'm guessing you have a conservatory, and an extractor fan between the conservatory and the house to bring the warm air into the house automatically. You want a pair of thermostats.............one calling for the heat, and the other holding off until there is available heat.

Or maybe this is about temperature control within a greenhouse to prevent overheating.

Years ago when I came up with the above system for pulling the heat in from a conservatory, an electrician told me that any common thermostat has an unused terminal which potentially makes it reversible. Now that so many thermostats have become digital and programmable, I don't know whether this still applies. I suggest a visit to your local electrical wholesaler. This is the sort of thing which they love to sort out.

 

[RogerS]

That's a nifty controller Robert. I may well use something like that for the oil boiler/termal store combination if the controller does what I think it does.

Mike....no conservatory although the polytunnel could well double up for one! No, it's to take the hot air that's at the top of the house..remember that the atrium (for that is almost the size of it) is rather large and there's a noticeable amount of hot air upstairs on the landing. So I plan to have a grille in the ceiling in an unobtrusive spot and blow that hot air back down through some insulated ducting to ground floor level.

 

[Mike G]

Ah yes, I remember now. Can I suggest you use the minimum size fan which will achieve the necessary air movement, rather than a big (noisy) fan creating draughts.

 

[RogerS]

I've expanded my thinking on this one.

Story so far...

The hall (atrium) is very, shall we say, capacious and a bugger to heat. Lots of hot air on the upstairs landing though. So my thoughts were to have some ducting and a fan that would suck the hot air on the landing and gently blow it out at floor level in the hall.

But...while thinking about en-suites etc, :idea: Currently we have one en-suite without any window or extract facility, one utility with an out-of-reach window and no extract facility, a cloakroom downstairs...no window, no extraction. A new ensuite to go in..window but no extraction fan...main bathroom ..an out-of-reach window. And the kitchen (not a great fan (no pun intended) of cooker hoods.

So......how about getting one of those MVHR units and duct up all of the above-mentioned rooms (insulated ducting naturally) and feed to the input side of the MVHR which then vents outside (bonus...only one hole needs to be cut in the walls rather than one per room) and on the side that is usually fed from an outside source, instead capture the hot air at the top of the landing and pass that over the reclaimed heating fins and back down to floor level as before?

Cost of the MVHR unit will be offset by the cost savings in not buying an ICON fan per room and cost of holes in very thick walls.

The house is not going to be hermetically sealed and so I reckon that there will be enough fresh air getting in along the way from elsewhere, door opening etc.

Sound like a plan ?

 

[9fingers]

ISTR a comment from you about only heating rooms you are using. So why actively heat the hall at all. Inhabitants will only be in transit for short periods and visitors arriving from a cold outside won't notice anyway.
Bob

 

[RogerS]

ISTR a comment from you about only heating rooms you are using. So why actively heat the hall at all. Inhabitants will only be in transit for short periods and visitors arriving from a cold outside won't notice anyway.
Bob

Yes, you are correct, Bob...I think in hindsight that we do need this area at least warmed up a bit. We seem to transit it a fair bit or maybe it's an age thing...blood thinning !

I guess the real question is whether there will actually be any heat transfer since the incoming air is already warm..so maybe not complicate the issue...just duct all those rooms to one extraction point...only thing is how do I only turn the extract on when the room has been or is in use.

Ah, I know..'Smart' switches :lol:

 

[Tusses]

could you use an air to water heatpump - inside, up high - and put the hot water back into the heating system ?

 

[9fingers]

ASHP only work efficiently with low water output temperatures no more than 50 C such as found in UFH systems and I think Roger has ruled those out. He has also previously ruled out oversized radiators to make best use of condensing boilers.

hth
Bob

 

[RogerS]

ASHP only work efficiently with low water output temperatures no more than 50 C such as found in UFH systems and I think Roger has ruled those out. He has also previously ruled out oversized radiators to make best use of condensing boilers.

hth
Bob

I've ruled out UFH. We've got it at the rental and we both hate it. I propose to make best use of condensing boilers but not to the extent of having oversized boilers. Good background heat with normal sized radiators is fine. I had a brief moment of concern as I noticed that LOML liked her shower hotter than me and if one was running at a lower boiler temperature then I was concerned that it wouldn't be hot enough. So I got the meat thermometer out and stuck it i the shower at her setting...41 degrees. So all good then.

 

[Tusses]

I was more thinking of pre heating the water before it goes back through the boiler.
Water is a lot easier to move about than air.

I've never played with heat pumps, so it's all just a thought experiment