House replumb, new combi, lose the cold water storage

[ALEC1]

With the vrc470 the controller can be mountd in the boiler fascia with no indoor sensing, or wall mounted, with or without room sensing

 

[RussTaylor]

Cool thanks.

The boiler is going in my downstairs loo in a lean to on the back of the house which won't be very indicative of the temperature. I think it's wireless so I was going to put it in my hallway, it looks quite flash so should be fine.

Still trying to decide if my loo will need a rad, or there'll be heat from the boiler anyway ...

Cheers

 

[ALEC1]

whether you activate room sensing or not is up to you...if its in the boiler it won't be displayed as an option, or you wont be able to select it...

It may help if you know that all boilers in Germany have to have an outdoor sensor, so the technology has evolved to not need room sensing...and from experience those that have it on out door sensing only find it works fine without the added information from the indoor sensor.

Can't help you about the loo radiator though thats up to you...

 

[RussTaylor]

Does the boiler give off any heat? It's a small loo and a massive boiler I can retrofit one after if I need it.

That's interesting, as it's wireless I'll have the option to move it out of the hall if I don't use the room sensing/fiddle with it much/want to show off my £4k of new heating somehow. The hallway is different to the rest of the house anyway. I guess if I fit a quality (rather than £8 wickes) rad TRV that'll help a great deal as well?

Thanks for all your time, you're not in Somerset are you? I'll need a Vaillant service guy for the future.

 

[ALEC1]

I would put TRVS in rooms that are infrequently used and may be bedrooms...but you want to avoid a situation where there is no open circuit for the compensated flow, as it will be running all the time there is demand for heat, albeit at a fluctuation flow temperature..

assuming the radiators are correctly sized, then you should be able to set up the controller to match the heating requirements almost perfectly...without the need for TRVs..

they do help with balancing systems but as said a few radiators should be left open as the boiler will be expecting to loose heat!

 

[RussTaylor]

Great, thank you! I hadn't considered that.

I'll leave the living room wide open along with dining room as it has doors opening onto the garden. I'll control the temperature there by the controller and use TRVs to tune the rest of the house to match. I'll get a better TRV for the bedroom as that radiator is oversized I think which was my mistake.

Wonderful, thanks a lot.

 

[ChrisR]

It may help if you know that all boilers in Germany have to have an outdoor sensor, so the technology has evolved to not need room sensing...and from experience those that have it on out door sensing only find it works fine without the added information from the indoor sensor.

We can all quote delighted customers, and annoyed ones, as we choose....
As I said check some German forums. You will see plenty of complaints about boilers without indoor sensors.
They have not evolved - the ones without the indoor sensors are the cheapo systems.
(Not being flash cos I did German - Google makes it easy.)
If the boiler's only responding to outside temperature it doesn't know how cold the house got overnight. If at 7am when it comes on it's 10º, you get heat for the 11º difference ( to heat to 21). But if it was freezing at 3 am the house will be extra cold. So Die Frau stays cold until it catches up.
Sure it saves lots of gas!
I know not all systems are that bone, but I know many that are.
(Found a couple of German installers saying that as long as it gets to 21 eventually it meets the German spec so it's OK stop moaning... Jawohl!)
Your "evolved" systems might take the temp of the return water but that only tells the system how much heat the rads are losing, not what the temperature is. So it has to wait...

If the user's cold, he has to fiddle with a "parameter" (which the installer could only guess at) to get it hotter, which of course gets left "high". So we go in after the installer's vanished and find things set oddly, and hear "but it couldn't have been set right so I changed it". It's always an education to delve into WC systems and see how they were left.

If you want it "simple", measure the room temperature! How much evolution does it take to get to where any Control Engineer on the planet would start?
They only avoid it to make it cheap to install I expect, that's what I'd do if I were flogging boilers. Flashy brochures, gullible installers, sorted.

nb Russ TRVs can only reduce the heat not increase it. WC systems seem to rely heavily on that because to be warm enough at all times the parameters have to be set high. Yeah it works ok like that, if you must.

 

[ALEC1]

Vaillant and Viessman both seem to over come this issue with a night set back temperature. As previously said the actual result of these controls will depend on how people interact with the parameters of the controller..

It seems then that Vaillant do not share that much information with any installer.. It must be a big company thing....

The benefit of these controllers is the multiple parameter that can be varied.

 

[ALEC1]

And if a regularly occupied space really lost 10c overnight I would suggest the issue is the lack of insulation, not the heating!!!!

 

[ChrisR]

[quote"Alec"]And if a regularly occupied space really lost 10c overnight I would suggest the issue is the lack of insulation, not the heating!!!![/quote]
Alec - EXTERNAL temperature difference is 10 degrees not internal.
It would be better if you could try to engage brain before embarrassing yourself with a silly wisecracks.
----

The benefit of these controllers is the multiple parameter that can be varied.

That's Ok then? We can tell our customers that they have to get the installers book out, check with the manufacturer because it's not explained very well, then

"interact with a parameter"

.

A programmable thermostat with numbers on, like degrees, will suit some people better.


Oooh!
Can you charge people extra for having parameters to interact with?

This is obviously what NO customer wants.

 

[ChrisR]

even my forty year old system had an outside thermostat.

That sounded like a frost stat, so not normally in use during the day. They used to be common.

 

[ALEC1]

that's why the Vaillant and Viessmann offerings are so good, they are just like programmable thermostats..

And with the vrc470 on a wall set up to read indoor temperature you have just what you want..

 

[ChrisR]

I'll give you that things look like they're getting better than the nonsense we've been offered before, as I've said elsewhere, though tbh I (we?)don't know much about how these actually work. Give them a couple more years and we'll start to learn how they go.
This is acknowledgement that they've been doing it wrong up to now, despite all the assertive spouting of brochure twaddle..

There's been so much lies and deception for years I'll reserve judgment.

It's a pity they leave out internal temperature measuring on their cheaper systems, like other manufacturers do. And it's a pity the odd gullible, volumble, ill informed installer thinks it's clever to do so.

 

[Agile]

I would put TRVS in rooms that are infrequently used and may be bedrooms...but you want to avoid a situation where there is no open circuit for the compensated flow, as it will be running all the time there is demand for heat,

Surely as a "better than most"!!! installer you will have fitted an auto bypass which will prevent that problem?

 

[RussTaylor]

So rather than leaving a couple rads open I can set trvs on all of them and put an auto bypass in the system somewhere? This sounds good, would allow me to turn a room down rather than turning the whole system down.

Where does the autobypass sit please? Is it plumbed in at the boiler or do you plumb it in before a radiator to bypass it when the trv is closed?

All very interesting and clever stuff, didn't realise there'd be so much to central heating

Thanks again