Cold Showers After Some DIY Central Heating Work!

[jagillham]

I expect this problem is self inflicted, but I am after some help.

We have a GreenStar 24i junior installed by British Gas about 6yrs ago now. The house itself is a 1903 terrace, which has never really got above 'mild'.

Anyway, we have some money now to do the house up, so along with adding better insulation I decided to swap the battered single radiators for new double ones from Wickes. Along with this I have moved a few radiators to better locations, replacing the copper pipe with JG 15mm PEX. To do all this I've had to drain the system a couple of times.

This was all great for a few days, the house got up to a toasty 21 degrees C the other night, this is before the new insulation etc. However yesterday morning and today shower problems have developed. After a few minutes the shower goes freezing cold. Turning the shower off and back on gave a few more mind of hot. This is just a normal mixer shower.

From having a quick read this morning it seems like some kind of chemicals should be used when drained down, which I did not. Is there anything we can do? I'd get an engineer out, but we want to save cash, and also both work full time, so will struggle to have time for one to come around. The wife is not too pleased with starting the day on a cold shower, so I need this sorted ASAP.

Any help would be most appreciated.

 

[jagillham]

A bit of an update:

The boiler engineer came out today, and says that the water flow downstairs is not enough to make the boiler fire.

To me this does not make sense, because nothing has been changed on that part of the system, and it has been working for about 6yrs perfectly fine exactly how it is. Same boiler, same taps, same pipes etc.

Their only suggestion is to change the flow switch and the descaler, but not really willing to say this will fix the problem - a rough price of £300!

Anybody got any ideas?!

 

[joe-90]

Well if the boiler gives hot water to begin with then the flow switch must be operating.

Sounds like the plate heat exchanger needs cleaning.

I'd try one of the proprietary flushes before getting someone out.

Three hundred notes?

 

[jagillham]

I'm a bit of a numpty, so this could be totally wrong. But could the hot water to start be something to do with the heating being on?

Is there anyway of inspecting the head exchanger, or is it a case of running the flush and then seeing if the problem fixes itself?

Finally, could what they are saying be right? I'm a little begrudged to pay a call out fee if they are nowhere near the mark.

 

[joe-90]

Have a look around the site.


http://www.diynot.com/forums/viewtopic.php?t=55906

 

[jagillham]

I was just reading that exact topic

 

[jagillham]

I've done a few more tests, running the hot water taps the boiler fires up for a min or so with the water running hot. After that it goes into a cycle of fire up for about 2 seconds, before cutting out then, firing up a second or so later. Once I turn the tap off, the boiler then fires successfully for 10 secs or so.

Does this help narrow down the issue?

 

[joe-90]

It's a bunged up plate heat exchanger.

 

[jagillham]

That was the conclusion I was coming to reading around, but miffed the engineer didn't even mention that as a possibility.

Is there a quick fix to this, I'm not sure I can face another cold shower tomorrow morning?!

Thanks very much for your help

 

[joe-90]

Maybe he meant the plate heat exchanger when he said - descaler (knowing that you wouldn't know what he was talking about).

 

[sooey]

You may have a knackered main heat exchanger now if you didn't bleed the air out of it before you fired the boiler.
Joe will explain, he's gas safe you know....here's his card.

http://oi50.tinypic.com/2z5p0ma.jpg

 

[joe-90]

 

[jagillham]

Unfortunately not, he was talking about the unit on the pipework coming in. Said it looked like it predated the boiler, and wanted changing every 10yrs or so.

I was at work, the wife was at home. He called me up for 10 mins, which was the duration of his stay apparently. The 'official diagnosis' was the boiler is fine, but it was a lack of flow not triggering the boiler. A plumbing problem basically.

We've not paid anything yet, and they apparently getting prices for the parts. The call out charge (inc 1st 1/2 hour) is £90... I'm wondering if their is grounds not to pay it.

 

[joe-90]

That's more than a heart surgeon. I wouldn't pay them a penny.

 

[b13kal]

Unfortunately not, he was talking about the unit on the pipework coming in. Said it looked like it predated the boiler, and wanted changing every 10yrs or so.

I was at work, the wife was at home. He called me up for 10 mins, which was the duration of his stay apparently. The 'official diagnosis' was the boiler is fine, but it was a lack of flow not triggering the boiler. A plumbing problem basically.


From what he is saying here its the flow switch or micro switch

From what your saying it can't be a flow switch otherwise the boiler would not fire at all!!

From what you have explained it sounds like the secondary heat exchanges is faulty and best to replace it and not clean it. Also flush the radiators out with chem and add inhibitor after the flush