New boiler for vented system

iep

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Our old Glowworm EnergySaver60 has started to make a rather alarming 'whumph' sound when the burner lights.

This only happens when the boiler has been running for a while and has then been shut down for 30 mins or so (once the house thermostat stops calling for heat). Upon the thermostat calling for heat again, the 'whumph' noise occurs. It's like the normal sound of the burner lighting but is about 10 times louder.

The noise does not occur if the boiler is started from cold (ie in the morning after being shut down all night) or if it has only been shut down very briefly (ie when the internal thermostat switches the burner off because the return temp is high enough).

My guess is that either the electrode is on its way out or that the corrosion in the condensation tray has finally pinholed the tray and is now leaking onto the burner.

Anyway, if it's the electrode, I'll have it repaired. If it's the condensation tray, it's time for a new boiler.

Which leads me (finally) to the question. If I'm looking for a decent vented system boiler, would the WB 18ri or 24ri be okay?

Also, since there is very little priice difference between them (and theyboth modulate down to a similar output level) is there any reason not to go for the 24ri?

The Glowworm is an 18kW boiler but we have only had to run it in summer mode up until now this year (8kW).

FYI, we are happy to keep the vented system and there is no real advantage in a 'system boiler' within our installation.

Cheers,

iep
 
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There is no point in fitting an oversized boiler.

I like the 18Ri and they are smallish, neat looking and very quiet.

They should be serviced anually and that needs access space above them to do the job properly.

I may fit one next week for someone.

Tony
 
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Hi Tony, thanks for your thoughts. I'll take that as good vote of confidence in the 18Ri.

Once installed, there will be approx 30cm of space above the boiler, is that enough to allow easy access for servicing?

I was hoping the glowworm would see the winter out but I don't like the new 'whumph' sound at all.

Does this sound dangerous to anyone? I had it serviced back in May and the guy assured me that it was safe despite the corrosion in the condensation tray.

Cheers,

iep
 
You have to differentiate between 300mm above the boiler casing and 300mm above the top of the flue.

The makers ask for about 200mm above the casing to accommodate the flue. I would want to see ideally 400mm above the casing as a minimum.

The system should ideally be converted to a closed one. A 18Ri can still be used but you need an expansion vessel, PRV and filling look fitted external to the boiler.

Tony
 
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I think there should be about 400mm above the case so that should be okay.

Converting to a closed system would be possible but I have a couple of questions (if you have time):

1. How much is an expansion vessel likely to cost and can what restrictions apply about its location?

2. What advantages would we see in moving to a closed system?

3. I recently re-plumbed the entire system in JG push fit. Did a very careful job and used the double o-ring inserts throughout. So far it has been really good with no leaks etc so I'm just nervous about introducing problems if I go from a low presure open vent system to a higher pressure sealed one. Would you anticipate any issues?

I guess though that one of the advantages of a sealed system is that it will be easy to spot if there is a problem via the pressure gauge.

Cheers,

iep
 
EXV costs about £20 and can go anyway as long as it will not freeze and is accessible for repressurising every 2-5 years.

Also needs PRV and dischage route as well as a filling loop.

The advantage is that over time it should be less likely to get sludged up, its about 2-3% more efficient we are taught and not prone to pumping over which destroys rads in days/weeks.

Tony
 
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Looking around at other boiler options I noticed the viessmann vitoden 100-w compact which slooks pretty good with a perfect 19kW power rating, up to 97% efficiency and very low operating noise. It also seems to be ready for weather compensation controls which would be very useful given the wide temperature range that we get day to day where we live.

How does Viessmann compare to WB? The ten year heat exchanger warranty looks decent.

Cheers,

iep
 
More reliable we would say and it has a five year warrantee if fitted by an approved Viessmann installer.

Tony
 
if you are looking at vented boilers I would look at the Intergas 18ov

small compact, 10 year warranty on the hx, 3 warranty on the rest, 6.1-18.2 kw range.

also has weather comp and can take open therm controls that the viessmann cant
 
If the boiler has spark ignition sounds like needs new electrodes.
Cheap and easy fix. Boiler should run on for years.
 
also Intergas has less moving parts then viessmannn and does not suffer from trapped air in the hx like the viessmann
 
The Viessmann does not suffer from trapped air in the HE if the installation is correctly commissioned by the installing engineer AND the system is not messed about with by DIYers or decorators.

About 3% of the calls I get are following someone draining a system when they dont know how to refill and vent the air.

Tony
 
Cheers guys.

I'll get hold of a new electrode and see if that helps. I'll also check out the state of the condense tray while I'm in there and see if I can spot any signs of leakage.

If it does seem to be on its way out, I'll have a look at the intergas boilers mentioned. Not heard of them before TBH.

BTW, what are open therm controls?

Cheers,

iep
 
Sounds like you are a fan of the Viessmann Tony?

Our's is a difficult house to heat due to location and construction so I don't mind spending a bit more if it means getting a reliable efficient system but there is a lot of choice out there.

Cheers,

iep
 
Your cheapest option may be to get your RGI back to check why you`re getting explosive ignition,it may be fairly easy and cheap to repair.
 
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