Combi with an Immersion Cylinder as back up?

[ChrisNason]

Is it possible to put an Immersion Cylinder in to a Combi System?
I've had a look at the Valiant 937 with 2 small Stainless Steel storage vessels but they do seem small and you can't get an electric back up of an Immersion.
It would be nice to still have hot water if the boiler fails.
Any suggestions?

 

[Corgigrouch]

Yep it is possible... pipe the heating circuit as a Y plan system and connect your main bathrooms to the cylinder and feed your cloakrooms / utillity to the DHW part of the combi... but if your boiler is getting on a bit, then why not just replace it with a conventional boiler and cylinder.

 

[gas4you]

To have a 937 supplying just the cloakrooms or kitchen would be a complete and utter waste of time and money

 

[ChrisNason]

I'm presuming there is no way of putting the cylinder in series after the combi as in the 937?
If not then I have to have a non combi Boiler Cylinder and Expansion?
Or, saying it another way, what is the minimum you need to get mains pressure and some store for an immersion?
I'm the one with a 450mm entrance to the cupboard (but 570mm inside) with plenty of height and depth.

 

[Corgigrouch]

To have a 937 supplying just the cloakrooms or kitchen would be a complete and utter waste of time and money

The question was "Is it possible?" not " is it wise?" Many folk who ask here do as they wish in the end, not as they are advised

 

[Corgigrouch]

I'm presuming there is no way of putting the cylinder in series after the combi as in the 937?
If not then I have to have a non combi Boiler Cylinder and Expansion?
Or, saying it another way, what is the minimum you need to get mains pressure and some store for an immersion?
I'm the one with a 450mm entrance to the cupboard (but 570mm inside) with plenty of height and depth.

I'm sory, I don't get it...Why would you want to pay for a combi and then stick a DHW cylinder on it? Just fit a standard boiler and cylinder with an immersion... Your goals have then been achieved. If you want mains pressure DHW then fit either an unvented or a heat bank

 

[ChrisNason]

I'm presuming there is no way of putting the cylinder in series after the combi as in the 937?
If not then I have to have a non combi Boiler Cylinder and Expansion?
Or, saying it another way, what is the minimum you need to get mains pressure and some store for an immersion?
I'm the one with a 450mm entrance to the cupboard (but 570mm inside) with plenty of height and depth.

I'm sory, I don't get it...Why would you want to pay for a combi and then stick a DHW cylinder on it? Just fit a standard boiler and cylinder with an immersion... Your goals have then been achieved. If you want mains pressure DHW then fit either an unvented or a heat bank

Heatbanks won't go in. Unvented requires Boiler Cylinder Expansion and various pipes pumps etc. I'm just trying to get it all in to a small space.
If I stack them all up on the outside wall (570 x 2400) would it work? The combi only falls down on the fact you have nothing if the boiler fails.

 

[Corgigrouch]

Other than the requirement for a certified plumber for the unvented, then it is no more difficult to fit an unvented than it is to fit a vented cylinder...Don't forget that the vented cylinder will still need the piping for the header tank and the cylinder won't take mains pressure.. If you are worried about the once in a blue moon time that your combi develops a fault. you will spend your life worrying about what ifs... If you aint got the room, then you aint got the room

Hows about something like an Ideal Istore (Other manufacturers build similar stuff but better, perhaps the others can advise as I don't tend to fit this kind of stuff) they are a boiler and cylinder built in to one and could well fit in to your prescribed space

 

[mickyg]

just fit a 937....no cylinder is necessary.. its very reliable. have the system properly flushed and fit a magnaclean(or similar)....in the unlikely event that it does go wrong then theres always the kettle .............

 

[simond]

Over 50% of our 937s have had Vaillant service out to them.

Normally 3 times. First time to diagnose the shift load pump. Second time they send a Glowworm bod who decides not to fit the water bearing part, only the pump motor. Which makes no difference.

Then the third time a Vaillant chap comes round and fits the right part. it's a non return valve in the pump, apparently.

 

[ChrisNason]

Hows about something like an Ideal Istore (Other manufacturers build similar stuff but better, perhaps the others can advise as I don't tend to fit this kind of stuff) they are a boiler and cylinder built in to one and could well fit in to your prescribed space

Thought you were on to something there. Istor is exactly what I want but it's 560mm wide.
This forum is full of tales of failed boilers. I always default to good resilience plans... so for heating I have fan heaters and an open fire. For hot water I'd like a backup system. And the present (inefficient) system often needs the immersion for quick re-heat.
Anbody else got views on the Valiant and reliability?

 

[Corgigrouch]

Don't forget that people only come here when their boilers are broken so you can expect a high degree of broken boiler stories... Similarly they have tried to either fix it themselves and cocked it up or had it installed on the cheap and so not installed correctly. You can fill your house with emergency systems and back up systems ad infinitum but you would have no room to live...Just accept that you may have to have a cold shower every five or six years.

Any way have a rummage about and see if anyone does a slimmer system than Ideal.. I used the Istore as an example but I think that the Vaillant will give you years of trouble free service

The Istor is essentially a conventional boiler connected to an unvented cylinder with all the gubbins, pumps, valves and safeties built in to the casing to make it easy and quick to install in to new builds so an unvented with a small cylinder can still be an option

 

[ChrisNason]

Valiant is the best option so far

 

[Agile]

If you must have a backed up system then the best solution is a CW cistern in the loft and a slim vented cylinder feeding the bath and everything else off the combi.

Use a cheap 28 kW combi properly fitted and you have backed up the boiler heat AND the water supply.

You will have mains water shower from combi and 25 li/min of HW rapid dump into the bath with a backup immersion electric heat.

That system will cost less than Dave's 937 and give you double backup.

Add a 150w inverter and a couple of old car batteries and you can power the combi during a power cut and have a FULL backup during an Iranian nuclear atack until the radiation sickness gets to you!

Tony

 

[ChrisR]

Or fit a Rinnai water heater - on the outside of the building.

Or fit a heat-pump type air con unit.. Then you're cool in Summer and have a few kW of heating available too.