Choosing vaillant ecotec 838 or 837

[neilw]

Hello,
I'm in need of a new boiler, my current Ariston while very good is 10 years old and I may as well put the £150 I need for a new secondary heat exchanger towards a new one.

My boiler installer (who did my ariston) has recommended a Vaillant as probably the better choice, though he is installing some worcester and has no real bad words against them (or ariston) but think the vaillant is slightly better (stuff about stainless steel/aluminum stuff, etc )

Putting in my stats (it's a 4/5 bedroom, 5 person house with loft conversion as fifth bedroom/ensuite, two bathrooms plus one more with electric shower) and maybe about 220-250m2 usable area that I roughly calculated.

The outcome was either a Vaillant ecotec exclusive 838 first and ecotec plus 837 second or the other way round depending on the options chosen that I changed slightly.

Can anyone tell me the main difference and which would be better suited?

(the equivalent worcester came out as the 42cdi and all three of these are roughly the same price).

 

[3DGuy]

I'm not an expert but we had an 837 installed in our 3bed semi with 2 people in. The reason we went up on the spec over a smaller model was the increased flow rates this one went up to, was 9lpm on the lower ones and this was up to 16lpm (water pressure on mains depending).

However for a 5 person house I would have thought not to use a combi but a more conventional style boiler/ pressurised water tank as the water usage would be far greater. with a fair few more bathrooms/rooms than we have.

Just my thoughts on that because if its a combi, if both bathrooms run at the same time the flow rate is basically halved. If you have a low water pressure, you could end up with 2 bathrooms that cant be used at the same time defeating the luxury of having two in the first place. A stored tank pressurised would result in both and other rooms being able to be supplied and all be useable.

Just my 10C (correct me someone else - trade plumber etc if I'm a little mixed up or not)

 

[muggles]

You want to put a combi in a house that size? I wouldn't recommend it, you need a system boiler and a hot water cylinder

 

[neilw]

thanks for the replies but note the 'loft conversion', we have no place to put a tank other than on outside next to the chimney

ignoring that, and assuming a combi will be ok (which it is to be fair as my current ariston does a half decent job, it's just getting old now) which of the ones I mentioned will do a better job?

 

[3DGuy]

I've no experience with it but came across it when looking in to the one we were going to get.

What about the 937?

http://www.vaillant.co.uk/products/domestic-boilers/combi-boilers/ecotec-plus-937/

Has a hot water store in it? Slightly larger and I don't know a lot on it just I saw that one. Might be an option?

Suggests this - "Typically a 3/4 bedroom detached house with one or two bathrooms."

 

[jeff the gasman]

Hot water flow is entirely dependant on incoming water mains supply and any resistances an appliance has.
If thermostatic showers are used a 35 KW combi is more than adequate and I have yet to have a complaint.
Non thermostatic showers can cause scald and freeze shower experience.
Vaillant 937 looks brilliant and works well but didn't see marked improvement on standard combi and more things to go wrong.

 

[3DGuy]

Hot water flow is entirely dependant on incoming water mains supply and any resistances an appliance has.
If thermostatic showers are used a 35 KW combi is more than adequate and I have yet to have a complaint.
Non thermostatic showers can cause scald and freeze shower experience.
Vaillant 937 looks brilliant and works well but didn't see marked improvement on standard combi and more things to go wrong.

I believe its 1 electric and 2 standard bathrooms + Kitchen etc? Cloakroom toilet also?

Potentially an electric shower (in ensuite?) could be on with that scenario (not affecting boiler water delivery), kitchen sink hot tap, both bathrooms showers and (unlikely) but a WC cloakroom sink briefly.

Is that a summary of all the hot water at worst case could be in use? I'd have thought the main issue would be the showers together or baths, but if you get a top dog combi you might be ok with 2 bathrooms on it and the en suite using an electric.

 

[neilw]

My friend just moved into a new house where the previous owner fitted a 9 series vaillant with the second tank (he is an installer so presumably got a good price). If you want to make use of the second tank you have to leave eco mode on and effectively the second tank is always kept warm.

His bill (there are only two of them in the house, and it's a small house) was over £500 for the first month, so he knocked off the eco mode to stop it keeping water warm and the second tank. His monthly bill is now less than a third of this.

This has put me off the 9 series

tbh, the radiators are always sufficient with our existing boiler and the water has only just become an issue simply because the exchanger (I thought it was the diverter valve) needs replacing. We rarely need two showers together at the minute, but yes taps on in the kitchen does affect a shower.

So I'm happy with a combi, just needed to know what people thought the difference between the two I mentioned were or if they weren't suitable.

 

[3DGuy]

My friend just moved into a new house where the previous owner fitted a 9 series vaillant with the second tank (he is an installer so presumably got a good price). If you want to make use of the second tank you have to leave eco mode on and effectively the second tank is always kept warm.

His bill (there are only two of them in the house, and it's a small house) was over £500 for the first month, so he knocked off the eco mode to stop it keeping water warm and the second tank. His monthly bill is now less than a third of this.

This has put me off the 9 series

tbh, the radiators are always sufficient with our existing boiler and the water has only just become an issue simply because the exchanger (I thought it was the diverter valve) needs replacing. We rarely need two showers together at the minute, but yes taps on in the kitchen does affect a shower.

So I'm happy with a combi, just needed to know what people thought the difference between the two I mentioned were or if they weren't suitable.

£500 sounds a bit of an exaggeration, even still the 1/3 with it off. That makes it a £2000 a year bill for just gas....What on earth is he running? Most 3 beds are like £800-£1.2k a year depending on usage. Did he keep the average temp at 45-50C 247 lol?

If that's put you off, I'm not sure on the 838, but I can voutch first hand that we really get on well with the 837. It's superb.

 

[muggles]

thanks for the replies but note the 'loft conversion', we have no place to put a tank other than on outside next to the chimney

You don't necessarily need one. Have a look at unvented cylinders such at the Megaflo or OSO Super Coil. You need a decent incoming main supply to run them, but if you have then these cylinders run off the mains rather than a loft tank, and would be a much better option for your house than a combi boiler.

Failing that, have a look at the Glowworm Ultrapower, which is a great half way house between the two

 

[Bunnyman]

837 is a better boiler out the 2. The 838 is to much trouble and rare as hens teeth. Spares may be rare in future, it was really only released to give better warranty . But if you get an advance installer you get 7 years on the 837 anyway now. The 937 is also not so good IMO,

 

[ACOperson]

The comfort setting on the 937 can be timed anyway - no need to have it on all day & night. Just 2 hours in the morning and maybe not at all after.

We've fitted a few 937's, as long as there is well sized mains and hot pipework with excellent pressure they work very well and can indeed run 2 showers.

 

[3DGuy]

The comfort setting on the 937 can be timed anyway - no need to have it on all day & night. Just 2 hours in the morning and maybe not at all after.

We've fitted a few 937's, as long as there is well sized mains and hot pipework with excellent pressure they work very well and can indeed run 2 showers.

This is useful. I was wondering about eh comfort mode. I cant remember if ours is on or off. We've been renovating for 10 months nearly and I really should check if that's on or off. If it is turned on now, I would be rather confused where that very high bill was coming on.

Currently we have ours set to be on for 1 hour in the morning and 1 in the evening as we don't stay there. Also we use tons of water (it feels like) for cleaning and washing kit up haha.

Our gas and electric use is hovering at about £52 a month. I'll check this asap as I'm wondering if the comfort modes on or not.

Sounds like the 837 is the best bet

 

[neilw]

Glowworm ultra? Would that be the 100 or 170?

1. Is this essentially a combi for normal use with a tank that I can call upon like say a vaillant 9 series?

2. If not, My memory of storage tanks is from 20 years ago having to have a second tank in the loft and having hot water only when it's turned on. Is this not the case?

3. Won't having a heated tank increase my bills massively?

Thanks.