Comments on Ideal Isar HE range

[John Rumm]

Hi,

Just about to embark on a loft conversion, and one of the first steps will be to retire our (17 year old) GlowWorm Fuelsaver 55F and install a combi - so as to get shot of the three tanks in the loft...

I was leaning toward the HE24 that is rated at 12 l/min for DHW, and is condensing with an efficiency of >90%. (although I am just about to measure our current HW flow rate to see how much of a disappointment

12l/min will be!)

Anyone got any comments on these boilers?

Heat loss calcs for the house suggest that 10kw ought to be more than enough for that side of things. The ideal range have the advantage of fitting in the space that will be vacated by the glowworm (many of the other options are a little bit to wide and would result in the loss of a kitchen cupboard - not a huge loss but would rather avoid if possible).

[Toby]

I've got the m30100 (30kW DHW / 25kW CH) and apart from a fragile user control, replaced FOC by Ideal, I'm happy with it. Comes with quite a good wall mounting plate so you can sort out the pipework in advance of lifting the boiler into final position. Doesn't make much woomph when it kicks in, the case is fairly small, and installation is straightforward. 22mm gas feed is highly likely to be needed. Best price I got from anywhere online or in person was the counter at Travis Perkins.

Never had a combi before to can't compare it with too many others, but shower and bath performance haven't drawn any complaints, sure beats a gravity shower upstairs. I only have thermostatic shower mixers, and the DHW thermostat is set pretty low so I don't have to mix water for washing up. I wouldn't complain at the delivery rate even on days like this. Like all things, there are bigger, better, faster boilers out there, but this scores fairly highly on the price/performance ratio.

[Christian McArdle]

24kW is pretty low. Consider going for the larger models. Unfortunately, I've noticed that the Ideal prices went up when they brought out the different ranges of Isar. Before only the 30kW model was available. Now the 24kW is the same price and each extra 6kW or so costs you about 100 quid.

Christian.

P.S. The Isar 24 is rated for 9.6 lpm. The Isar 30 is rated for 12 lpm. The Isar 35 is 14.4 lpm.

[John Rumm]

Aha - you spotted my deliberate mistake ;-)

Yup - it was the 30 I was thinking of... although perhaps I ought to go for the biggest

(did a flow rate test the other day and found that I get 16 l/min at the batch tap (gravity fed - with approx 10' of head). The cold supply is good for 22 l/min at best though)

[Christian McArdle]

Remember, those flow rates will be for 60C, not 40C. The equivalent flow rate for the 30kW combi will be just over 7.5 lpm, giving a fraction under half the flow of your current system.

Christian.

[John Rumm]

So buy the 35kw one then is what you are saying....

I make that 9 L/min assuming ground water at 5 deg C - output temp at

1. Mix a bit of cold and that should make for a decent enough shower.

Bath running time should still be acceptable - especially when you factor in the fact the current hot water system performance falls as you fill the bath because the rising main can't replenish the cold water cistern fast enough (combination of only moderate static pressure and a rather poor ball valve design) hence you loose head.

OK so where is the best price on a Isar HE35 to be found then?

[Toby]

It was from Jewson not TP but anyway for comparison this is what I paid:

Isar m30100 (~HE30) £518.59 (609.34 inc vat) Standard flue pack £34.28 (40.28)

Flue pack is unused as I switched to a vertical flue, so am open to offers....

[John Rumm]

Well that is about 220 better than any price I have seen so far.... me thinks a visit to our local Jewson is in order - thanks for that.

I wonder what they will do the HE35 for?

I take it there is no flue supplied with it at all? In my case I will take it straight through the wall the boiler is fixed to - so a standard flue sounds about right...

[IMM]

Go for the 15.5 litres/min Glow Worm condensing boiler if possible.

[IMM]

So, a 15.5 litre/min job will be about the same.

[John Rumm]

Not really - that would be 15.5 l/min of water 35 deg over ground water temp - I am getting 16 l/min of water at a usable temp - a 15.5 l/min combi would give approx 10 l/min at 60 deg. That said, that would still be adequate for now.

[IMM]

My ground water temperature must be about 8C at the mo. So that gives 43C at the hot tap at 15.5 l/min. 43C is the recommend temp for showers. The overall yearly performance will be very good.

[John Rumm]

The Glow-Worm 38CXi gives about the same performance (well 1 l/min better in fact) than the Isar for about the same money. The down side is it will not physically fit in the gap occupied by the existing boiler. Not sure how Glow-Worm compare reputation wise against the Ideal units these days either.

[IMM]

V good. Dutch design made in Holland, part of the Vaillant group.

[John Rumm]

Prefer my shower a bit hotter.... but either way something that can do

35kw or better ought to be good enough.

[John Rumm]

Not disputing the origin; as GlowWorm seem to "re-badge" all sorts of different makes of boiler, but how do you know the 38CXi is a Vaillant?

[IMM]

It isn't. Vaillant QC is imposed.

[IMM]

Raise the temp and bit and lower the flowrate to about 14.5 l/min and that is still a very good shower indeed. If you have an average shower of 7.5 l/min then you can run 2 showers off this model.