Please help:Netaheat electronic boiler

[luckydip]

My mother has a old netaheat electronic boiler which fails to stay on once lit. When the system is started it goes through the usual clicks and the burner comes on. After a minute or so the burner goes off and the click cycle starts again. After a a few attempts the burner comes back on and runs for a few minutes. After this the boiler and fan just stop altogether. At this point switching the system off from the mains and restarting fails to initiate the ignition process. The boiler casing is very hot to touch and the boiler thermostat is set on a 4.

Any help appreciated

 

[croydoncorgi]

Boiler's probably fine!
Check pump, and F&E tank.
Sounds like a circulation problem.

 

[luckydip]

I'm new to all this but here goes

1) Pump is Grundfos. I removed the silver screw from side and the rotor/propellor can be seen spinning. Does this suggest that it is OK? When this problem started and the system had been on for about an hour I noticed that the pipes either side of the pump where warm (10cm) and the pump itself was warm.

2) Is F&E the feed and expansion tank and would this be the one in the loft containing the ball? (Excuse my use of non technical terms). Do I jusyt have to check that it is filling OK?

 

[croydoncorgi]

No.
Check the F&E actually has water in it!

If pump turning and (apparently) water in the system, then the next possibility is an airlock somewhere preventing circulation.

If the pump and nearby pipes are warming up but NOT due to heat from the boiler, some sort of blockage is even more likely.

 

[MeMyselfAndI]

Pump may still be faulty I.E impellor has broken from shaft. Is the heating and hot water working O K ?

 

[croydoncorgi]

Pump may still be faulty I.E impellor has broken from shaft.

Good point.

 

[luckydip]

1)The expansion tank has water in it and the ball valve seems OK

2)I have removed the outer casing of the pump and the pump/shaft is turning OK when system powered up

3)There is no heating or hot water. I have tried each independently but same events occur. The boiler takes a few attempts to fire up. Once it gets going it stays on for a few minutes and then stops. The pipes to/from the boiler become hot (30cm).

 

[kevplumb]

whats the system layout ???

 

[luckydip]

whats the system layout ???

Not sure mate, I don't know much about heating. Two tanks in the loft, grundfos pump and two 3 position valves.

I bled the system and now the boiler fires up for longer periods and the heaters are starting to warm. However, after a couple of minutes the burner goes out. The ignition cycle begins, the burner stays on for a few minutes and goes out, and so on.

Ignition seems OK and pilot lights straight away.

 

[kevplumb]

try locking the valves open
lever on side/end

 

[luckydip]

try locking the valves open
lever on side/end

I have locked both valves on open position but this makes no difference.

 

[kevplumb]

are there any vent point's on the pipework ?

usually near the cylinder

 

[luckydip]

Is the vent point a place where I can drain water? On the bottom of one side of the cylinder is a point when I can attach a hose. This pipe is not warm, the pipes on the other side of the cylinder are very warm.

I have also noticed that there is a bit of steam/white smoke from the outflow from the boiler (outer wall). Never seen this before.

 

[alban]

Hi
I have similar problem as described with Netaheat 16-22 (20+ yrs old). Heating limps along on minimum setting firing up OK but for short periods only but if I crank up thermostat on boiler it shuts off finally after outer casing gets very hot to touch and then rads go cold. All rads warm up on min. setting. Tried draining system and now have put Superfloc in. I presume there's a problem with boiler overheating causing shutdown? Could this be scale in the heat exchanger leading to reduced water flow? However problem showed itself suddenly which is against that.

Pump seems to be working inasmuch as system didn't drain without pump but drained well with it on and all rads get warm. Don't know about motorised valve or where it is or how to judge if its working OK. Evidence of sludge as rads are cooler at the bottom. But on allowing water to run through from F&E tank it ran clear quite quickly.
I was going to leave Superfloc for 7 days then try to descale boiler with DS-40 for 12 hrs.
Any ideas? I feel the boiler works OK but it is in need of a declog or something.
Cheers for any help
Grahame

 

[Slugbabydotcom]

A vent lets air out and is at the top of whatever the plumbing item is.
A drain is at the bottom and lets water out.
The vent to which Kev refers is usually on the top pipe on the side of the cylinder with 2 pipes leading to it. The drain to which you referred earlier is on the other side and is for draining the DHW or 'hot tap water' from the cylinder