Heating is pathetic

Joined
25 Oct 2006
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Location
Warwickshire
Country
United Kingdom
I've posted here once or twice in the past about various problems concerning my central heating system but have never seemed to have sorted them out completely, or at best only to a limited degree.
The boiler is a Potterton Netaheat 10-16 Mk II F.
Pump is regular Grundfoss.
The controller is a mechanical/clockwork with a circular timer with little moveable segments to facilitate the on/off times, and two sliders for CH and HW.
I think the system is a 'W' plan whereby I can have hot water only or hot water AND heating, but not heating on it's own. And the hot water has priority.
Anyway, to my problem. I think it would be true to say that the heating has never really worked well, just better at times than others. We have been in the house for about 13 years.
By the look of things the heating looks a very diy effort, especially judging by the pipework routing in the airing cupboard, the only thing missing is a knot in the pipework!
Upstairs there are rads in all three bedrooms and one in the bathroom. Downstairs we have just one double rad in the living room, which is definately not adequate, and one rad, fitted by me, in the kitchen.
I have replaced the pump three times over the years, and the diverter valve once ( a second hand 3 position honeywell given to me and wired up for the 'w' sytem op).
I have also drained and mains flushed the system so many times I've lost count, removed the rads, taken them outside and flushed them both ways until the water has run clear as crystal and I've been blue in the face!
I've mains flushed the system backwards, forwards, upwards, downwards, turned off every rad in turn except one and done it all again, and repeated with every rad in the house several times over until I'm sure the system is surgically clean!
I have to fill the system from the bottom, (using a hosepipe as per mains flushing) to avoid airlocks, which I'm guaranteed to get if I just let it fill from the loft.
Anyway, after all this the heating is at best mediocre. By that I mean that the rads don't get too hot to touch by any stretch of the imagination, or to be more precise, the downstairs two don't. I can get the upstairs ones to get reasonably hot, and the bathroom rad to get very hot( its the first one off the feed plumbed into 22mm pipes) but if I do this the downstairs rads go cold, so I have to throttle the rest so that I get a bit of heat downstairs.
I have recently turned the pump up to 3rd speed (max) which improved things quie a bit, but only for a while it seems.
Now, the hot water is scalding......I mean it's almost boiling, so I edged the cylinder stat down a touch.......no difference... bit more.......still no diff, so I turned it down all the way......still no diff. Ahh, I thought, new stat and all will be well.......fitted new stat.....still no diff :(
I checked the operation of the motorised valve, and it seems it isn't responding to the cylinder stat at all. So I thought if it's stuck in the hot water position that would account for no or not very hot rads. So I moved the valve over to the manual position, which I assume is hot water AND heating position, but still no change.
My only thoughts now are that the rubber ball may have disintergrated and is partly choking the outlet to the heating side. I'm certainly not doing a drain down til the warmer weather's here, but would greatly appreciate any thoughts/advice/solutions from anyone of you guys.
The water from the rads is clear btw, I did put some anti-corrosion fluid in last year.
I apologise for the lengthy post, but I wanted to include all relevant facts, and a few irrelevant ones I guess.......but if anyone wants any more info just ask :)
Thanks for taking the time to read this far.
 
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i cant offer any advice but i have the same issue in regards to the heating being pathetic with the same boiler (i think), i've not done anything that youve done however and wouldn't really know where to start. will keep a keen eye on this one
 
It is really sad, and I know you will hate it, but it might just be a case that you have to fork out money for a pro to solve the problem. :eek:
 
Sorry, post is too long for a short attention span numpty like me :eek: :oops:
 
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maybe time for a new heating system? if you have been there 13 years and its older than that i think i would think about changing it to a combi boiler.
 
Either your MZV is working properly, or it isn't.

They're not hard to diagnose - you just need a multimeter, some patience, and the help of this site.
 
I did skim through all your posting.

What is clear is that you prefer fiddling and changing the odd part ( even using second hand ones! ) yourself rather than engaging a professional.

Its not possible for me to guess whats the problem from your posting and although I cover the Warwick/LS/Cov areas we would have to charge for a visit.

As you have chosen not to call any pro for the last 13 years its unlikely that you are going to change your approach now.

I suppose you could change the motor valve but I dont expect that is the problem.

Perhaps you should buy a thick pullover?

Tony
 
Tony if you can even skim through that at this time of morning you have mental stamina or you had a good lyin yesterday :LOL:
 
Apart from the expensive option of replacing the boiler, there are several possibilities: Boiler and/or rads too small, system wrongly wired.

To find out what size boiler you should have, use the Sedbuk Boiler Calculator.

To find out how much heat your rads give, use the Stelrad Elite Catalogue.

Provided the total of the rads is as good as the boiler calculator suggests, then they are OK and provided the calculated boiler size is between 10 and 16kW, then your boiler is OK and the problem lies elsewhere.

You say that the HW stat does not affect the HW temperature, which is nearly boiling, so that needs to be dealt with. Probably a wiring problem, but how it should be wired depends on which valve you have.

You say that you have a 3-port valve wired as W plan. Do you mean that you have a valve with five wires or one with three wires?
 
What is clear is that you prefer fiddling and changing the odd part ( even using second hand ones! ) yourself rather than engaging a professional.
Just a lickle reminder that DIY maintenance is what this site is all about.

Its not possible for me to guess whats the problem from your posting and although I cover the Warwick/LS/Cov areas we would have to charge for a visit.
Nobody is interested in your coverage area, or your charging policy, you self-obsessed, narcissistic, blinkered, bigoted excuse for an engineer.

As you have chosen not to call any pro for the last 13 years its unlikely that you are going to change your approach now.
Well why don't you lead by example and change your approach?

Perhaps you should buy a thick pullover?
****** ****.
 
[quote="zigg";p="
I checked the operation of the motorised valve, and it seems it isn't responding to the cylinder stat at all. So I thought if it's stuck in the hot water position that would account for no or not very hot rads. So I moved the valve over to the manual position, which I assume is hot water AND heating position, but still no change.
My only thoughts now are that the rubber ball may have disintergrated and is partly choking the outlet to the heating side. I'm certainly not doing a drain down til the warmer weather's here, but would greatly appreciate any thoughts/advice/solutions from anyone of you guys.
.[/quote]

i suggest you are closer than you think with what you said above, change the mzv and you should have a warmer house,

you seem to have done just about anything else you can have :LOL:
 
If you have this problem for last 13 years this could be a wiring problem however this not hard to check remove the top part of the mortarise valve and manually turn the valve to isolate the hot water system and try to see you get a better result
 

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