Vaillant Boilers

[eyeofthebeholder]

Hi Guys,

Looking into finally replacing my 28 year old floor boiler and have settled on the Vaillant 618 System Boiler.. I have already calculated up all the new rads BTU and the 618 is fine.

I have also selected the VRT360 for the control.

The question is do I need and what is the purpose of the VR65. I understand it is fitted next to the DHW cylinder and has a temp sensor which links back to the boiler to tell it when to switch on heat it up. Is this correct?

I am not going to fit a Vaillant cylinder, as quite frankly its hugely expensive, compared to others. I will probably keep the one I have (from Wickes) until I look into a solar heating solution in a few years. As this is the case, how does the VR65 connect to the cylinder?

Also, what cables do I need to connect to the VR65 and VRT360 to the boiler.

I will be getting in a local plumber to connect all the new rads up and fit the new boiler etc, but he has ask for me to buy all the equipment myself - so I get want I want - so I am making sure I am getting all the right stuff before he arrives!

Any info would be great

Thanks

Adam.

 

[gas4you]

The VR65 just connects to the cylinder stat.

The 3 port or 2 2 port valves connect to the VR65 as well.

The connection between the VR65, boiler and VRT360 is just 2 core .75mm cable. It is only low voltage digital signals going down this, and can be connected together anywhere.

You do NOT need the VR10 ntc as this only fits into a dry pocket on the unistor.

The VR65 will mainly let you set the boiler flow temp lower than the required DHW temp, but when DHW demand is called for the VR65 tells the boiler to run the flow temp hotter to heat the DHW up quicker and more efficiently.

If you have an exterior north wall I would recommend the VRT400 and trv's on all rads.

 

[eyeofthebeholder]

Thanks for the info.

How does the VRT400 work? I assume it detects the outside temp and switches on the boiler to avoid frost/freezing??

Do you not need a least 1 rad to not have a TRV, or doesn't it matter now?

Cheers

Ad.

 

[gas4you]

The VRT400 is a weather compensator/programmer/room thermostat that plugs in on the front of the boiler.

Depending on the outside air temp it makes the boiler heat the rad water up more on a cold day and less on a mild day.

Yes you normally do have one rad without a trv, the room where the room stat is, but as the stat is on the boiler, and the boiler has a built in auto bypass you put trv's on all the rads with the VRT400.

 

[eyeofthebeholder]

So if I was going to go with the VRT360 instead, I would put this in a room, but this room should not have a TRV on the rads?

If this is the case, I think it would be quite difficult to locate it as I was going to have 'non-TRV rads' in the 2 Bathrooms only. I was going to put the VRT360 in the living room where we will be installing 2x rads.

 

[simond]

Yep, VRT 360 is only to be used in a room where there are no rad TRVs.

The new VRC400 is quite tasty and backlit. Why not fit weather comp, it is only a few quid more, you already are buying 90% of the kit. And get the UniStor, the control functionality will be far better with a Vaillant NTC controlled cylinder. Wickes Smicks.

 

[eyeofthebeholder]

I would like to go for the Unistor cylinder but it is very expensive. Also, as I said previously, I will be looking at the solar heating which plumbs into the cylinder, so I don't really want to splash out on something now that may be the wrong.

As for the VRC400, does it also monitor the internal temperature or does it leave that 'function' totally up to the TRVs. Also, if I do opt for the VRC400, will I have to get a plumber that can programme the thing as well? The plumber I usually use is a bit of an old-timer and I don't think he's up to speed on these new technologies

 

[simond]

I would like to go for the Unistor cylinder but it is very expensive.

Depends whether you like quality or cheap.

Also, as I said previously, I will be looking at the solar heating which plumbs into the cylinder, so I don't really want to splash out on something now that may be the wrong.

Solar water is a total waste of money so I would agree that splashing out may be unwise.

As for the VRC400, does it also monitor the internal temperature or does it leave that 'function' totally up to the TRVs.

You can decide, it is configurable.

Also, if I do opt for the VRC400, will I have to get a plumber that can programme the thing as well?

You can programme it.

The plumber I usually use is a bit of an old-timer and I don't think he's up to speed on these new technologies

Probably not, better not get him to fit the solar then.

 

[gas4you]

If there is any chance of you wanting solar at a later date, I agree with Simon it is a waste of time and money if you want to do it to save money, then you should look at installing the Vaillant Aurostor cylinder.

Solar is good if your main objective is helping the environment, but realistically you will only save around £120 per annum on the gas bill.

 

[eyeofthebeholder]

What is in the Unistor cylinders to make them so expensive - probably 3 or 4 times over a standard cylinder??

What I was saying is that if we did go for the UniStor one it probably would not have the facility for the solar heating connections. We would be looking in about 2-3 years for this. I would rather look around at this time to make sure I get the right one etc. I am interest in the environment - everyone has to make sacrificies - but if I find the saves at that time are still too small I will not go for it

Basically - just want to keep my options open!

 

[brentwoodheating]

Did I miss something?
How do you get to all trv's? Surely where the 400 is located shouldn't have one?
Also, why would you want your stat mounted on the front of your boiler? Would you not still have an external one in that case?

 

[eyeofthebeholder]

This is how I see it - tell me if I am wrong.... :

The 400 is a weather compensator which adjusts the boiler for optimum running - eg on hot days it doesn't heat as much - on cold days it heats it more. This uses a temp. sensor located on the outside of the building.

The 400 does not have a thermostat in it. Instead ALL the rads in the house are fitted with TRVs and it is these that adjust the temp for each room. The boiler has a bypass valve in it so you do not need a rad without a TRV.

For this reason the 400 can be mounted on the boiler as it doesn't need to know the temp. of the room, but you can, if you want, mount the 400 away from the boiler in the room.

It does say in the documentation that you should only go for the 400 if your house is well insulated otherwise you will find it will not work as well.

Please view the specs at the end of this PDF: http://www.vaillant.co.uk/stepone2/data/downloads/e4/42/00/Controls_brochure.pdf

 

[simond]

The VRC 400 does have a stat in it, but this is not enabled when it is fitted to the boiler facia. So that part is your call, if you want a stat fit it in a suitable spot, and don't fit a TRV there.

Under the building regs it is OK in the boiler because it still is an electrical interlock based upon temperature of the living space.

The auroSTOR is a uniSTOR piped up with a second HE for solar.

Now go and spend your money before it is all gone.

 

[gas4you]

Don't forget you must have a north wall for the external temp sensor

 

[eyeofthebeholder]

Yeah - also got one of those from Wickes