Combi and domestic HW buffer vessel (domestic)

[looneyfitter]

Ill hopfully be attacking my system net week so ill obviously come crying when it doesnt work lol...

The schematic there is different to the way i do it tho. MY setup only has 1 pump and is pumped out the hot and into the top of the tank.

I cant see why they have the second pump drawing water past the taps to be honest.

Took possetion of my new 2010 viessmann 200w today. Gotta admit, it does look the danglies

 

[mickyg]

it will work, but your warranty on both the boiler and cylinder will probably be invalidated as I doubt you'd find a domestic manufacturer of the boiler or cylinder to allow the setup. Why not just by a glowworm ultrapower or viesmann 222. Its pretty much what you want already packaged up in a nice neat box with warranty intact

 

[looneyfitter]

The 222 was alot more expensive than the 200w. I already have the cylinder. The system can be st up so that it appears to be a normal setup.

I doubt an engineer would void a claim once he realised i was an engineer and a Premier fitter of there product.

Also a warranty can only be voided if they can directly prove that what has bee done is a direct cause of the particular fault.

As fair as i am aware, retro fitting is fine provided it isnt stressing the product.

I also designed and installled a system using a viessman to heat a buffer for a large launderette by using the Primaries to flow through the buffer directly.

The rep actually came out to have a look and was very impressed. 2x 35kw boilers, balanced header heated a 500l buffer tp 55 deg in about 10 mins

 

[looneyfitter]

Flow rate can be increased if inlet temp is higher as the boiler hasn't got to work as hard.(within reason) The only time you would have problems would be heating from cold( with increased flow tha is ) and even then it would just take longer. I'll be limiting to about 14l. Do you know of any 22mm inline flow meters?

Thanks for the interest gareth

 

[looneyfitter]

On another note, my boiler has weather comp which invariably gives a variable temp circuit. Now in general a WC setup takes care of itself, no room stats etc.

What affects do you think my underfloor heating circuits being fed from a variable temp circuit (as opposed to a constant temp as its supposed to) and having individual room stats will have on the system?

Edit:

IM now also thinking, should i have 2 WC cicuits fed from a low loss header, 1 for the rads and another for the UFH, that way both cicuits would be fully compensated.

 

[mysteryman]

As you have a Vitodens 200-W boiler, you can add a 'Sub Mounting Kit with Mixer' to it. This converts the boiler into a six pipe boiler, the third pair being the circs for the undefloor.

You can't do the job better than this. You won't need any other kit - the underfloor manifolds connect to the Sub kit.

 

[looneyfitter]

As you have a Vit-ens 200-W boiler, you can add a 'Sub Mounting Kit with Mixer' to it. This converts the boiler into a six pipe boiler, the third pair being the circs for the undefloor.

.

What comes with the sub kit mate? I have purchased spec'd header kits before today and they cost a bomb.

I can make a low loss header in about 15mins with ease.

So you recon,1 LLH then 2 no VT circuits pumped from that to the rads and the UFH? I havent rang Viesma-n as yet but does there WC system take internal temps for each VT circuit to aid warm up do you know?

Gareth

 

[looneyfitter]

Whats the plate heat e for mate? I was looking at the instructions earlier and couldnt see why. I have a full heatmiser setup at my house (each room individually timed/controlled) which is all controlled from 1 control pad or remote computer/iphone. I want to integrate this with the vitronic 200 WC but basically do away with the vitronic timeclock side of things.

What you recon.

 

[looneyfitter]

Ive got the latest 200w mate. Sorry i know what you mean, what i dont want to lose is the ability to turn off/contol the temp of rooms individually, so i will remove the ch demand feature from the UFH and just use the WC side of things.

We live in a 5 bed 3 story house and dont need all the heating you see.

I have only ever fitted W.C on commercial installations and i know how effective it is.

What is the plate heat e for? (some buttons dont work on my key board)

So i presume i add a second mi er circuit to do VT for the rads, and the boiler primaries will modulate in temp to give a second VT circuit.

Only prob i see with this is that the boiler would always give preference to the second circuit.?

Im a Ba i man in the past however have been converted to viessmann as there potential has just leaped out at me. So im still learning as to what they can do.

 

[looneyfitter]

I cant see a single reason why i would need any kind of secondary arrangement.

What i am saying is that without a 2 port between the rad primaries and the UFH circuit, the rad circuit could end up recieving a flow temp higher or lower than that required.

So if the UFH required 55deg say and the rads required 35 then the rads would end up with a WC temp of 55. You see what i mean? That is why i am sayin would it require 2no mi ers as the primaries would basically become a CT circuit.. As said mate i need to speak to Viessmann but thats how i am looking at the diagrams.

Towel rails will be left uncontrolled.

 

[Paul Barker]

Basically i have picked up a new 35kw 200w very cheap. However my house is fairly big and we have a 210l megaflow fitted indirectly at the moment.

My plan is to use the cylinder as a HW buffer and use the coil for a solar installation next summer.

I forsee a problem of compatability. You can do what you want now for your DHW needs but you would not benefit sufficiently from solar if you have a tank full of hot water all day.

To maximise use of solar you need as much of the tank alocated to only solar heat, particularly spring and autumn.

What I doat home is have n unvented cylinder heated via the one coil by solar only. The output of this cyl is fed to a backward TMV (single check valves removed) the cold branch of the TMV is fed to the taps, the hot branch to the combi.

In this way when solar is below tmv temp. it is sent via the combi for a top up. When it is greater than tmv temp it goes direct to the taps. Should one wish to one could fit a convensionally piped second TMV at this point to prevent vulnerable people coming to harm. We don't have anyone at home who needs this protection, we have brought them up to learn about dangerously hot water using the sense of touch.

The extra energy gained from the sun is significant when you utilise even the low energies which can pre heat your water beforfe sending it to the combi.

A combi without a diaphragm has no isses with sub TMV temperature water.

the system is utterly simple and reliable, and very cheap compared to all the elaborate ways manufacturers invent to fleece us.

 

[vulcancontinental]

I really enjoy this site and the diverse threads, especially this one but...

Occam's razor - "plurality should not be posited without necessity"

This is a casual observation, not meant to be critical.

Having said that, do the Megaflo's still come with the smaller immersion heater bosses? If so a 210litre model will come with two bosses and one immersion heater. Is it not possible to fabricated your own indirect immersion heater to be heated with water from the solar or boiler source? The tubes could be bent to give greater heat transfer length just as the electrical one is. Just a thought.

 

[looneyfitter]

Basically i have picked up a new 35kw 200w very cheap. However my house is fairly big and we have a 210l megaflow fitted indirectly at the moment.

My plan is to use the cylinder as a HW buffer and use the coil for a solar installation next summer.

I forsee a problem of compatability. You can do what you want now for your DHW needs but you would not benefit sufficiently from solar if you have a tank full of hot water all day.

To maximise use of solar you need as much of the tank alocated to only solar heat, particularly spring and autumn.

What I doat home is have n unvented cylinder heated via the one coil by solar only. The output of this cyl is fed to a backward TMV (single check valves removed) the cold branch of the TMV is fed to the taps, the hot branch to the combi.

In this way when solar is below tmv temp. it is sent via the combi for a top up. When it is greater than tmv temp it goes direct to the taps. Should one wish to one could fit a convensionally piped second TMV at this point to prevent vulnerable people coming to harm. We don't have anyone at home who needs this protection, we have brought them up to learn about dangerously hot water using the sense of touch.

The extra energy gained from the sun is significant when you utilise even the low energies which can pre heat your water beforfe sending it to the combi.

A combi without a diaphragm has no isses with sub TMV temperature water.

the system is utterly simple and reliable, and very cheap compared to all the elaborate ways manufacturers invent to fleece us.

Really interesting this. What kind of flow rates do you achieve tho? The idea behind the HW buffer is so i have a high flow rate/fast recovery. I suppose it would also be very simple to build a simple controller that recognises what the stored temp is at a set time, then if the Solar hasnt provided enough HW hen it would simply turn the HW circulator on and top the buffer up.

As per the Immersion idea, I was actually thinking about this a while back. You can still buy immersion coils so i could eiither make one or lengthen an immersion one. Not sure how long a 210litre coile would have to be? Ideas?

Would you think i would be better off using the existing primaries for solar or the fabricated ones?

Also are the santon prem plus cylinders stainless or glass lined?

Cheers for the lessons peeps.. Even with the eperiance i have, i learn summit new every day. IM like a bloody sponge for info lol

 

[mysteryman]

Going back to your questions of last night, Gareth, the rad circuit and the UFH are both weather compensated in the system I have described. The underfloor is mixed down to a lower temp than the rads. Your assumption that the UFH will be hotter is incorrect.

If you have a situation in which the UFH is in comfort mode, and the rads are in setback mode, the boiler will drive the mixer to full hot, and the burner will modulate right down to underfloor flow temp. The rads will be supplied at this low temp, but their output will be very low. This isn't really a problem, and if you want to prevent it happening, you can add an Extension pcb to drive a 2 port valve.

 

[Biggles..]

gareth

for the hot water pauls set up is almost the same as page 8 of the rinnai except instead of having two coils and passing the DHW through one he uses one coil connected to the solar to warm the cylinder and the output of that goes into the combi.

for flow rates the combi will be the restriction because if the pipes are sized right the cylinder will pass in excess of 40lpm.

as for the heating,in all fairness i think your going way over the top with LLH, mixing velves, VT and CT. simple zoning and WC will work better unless your going to start using proper controls measuring return temps,outside temps,circuit temps,floor temps and individual room temps etc.