New Parkray solid fuel burner... not heating water enough?!

4 Dec 2008
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United Kingdom
Hi. Please help if you can I'm going mad here.

We have an ex council house, it came with trianco TRH45 burner that heated the water for a simple circuit, header tank, hot water and 7 small radiators. No room thermostats, nothing fancy just the basic gravity fed system with a manual on and off water pump to feed the water around the radiators.
We lit the fire, when the water got really hot (took about 20 mins full blaze) pump went on, hey presto, hot house. We have an immersion system seperate, that heats the water in the cylinder, for summertime.
That was before.

A few months ago, the old burner finally split, and we had to replace it. After a lot of checking flue sizes and matching plumbing to make it the easiest swap possible, we installed a Parkray 99, same place, exactly the same chimney, plumbing, pump etc. (Well, a friend who is qualified installed it, we helped.)

The old burner was fabulous, it heated everything to a scary point, we had the pump running at all times in winter because if we turned it off the water went mad in the pipes. Hot water constantly, cosy house.

The new one is baffling us.

It does heat the water to an extent.... nearly hot enough to wash up with is the best we've had so far, but it won't get it properly hot. We're running the burner turned up to maximum air intake, and piling on tonnes of coal to get the fire really hot, but the heat doesnt seem to heat the water. therefore when we switch the pump on even after several hours of blazing fire... the radiators get filled with the lukewarm water and never make the house warm. All radiators are bled, although we don't think that can be the problem anyway because it wouldn't affect the not-very-hot tap water temperature, would it?

Parkrays are known for being hot as hell, and the internet is full of people
with this system panicking about excess heat... noone else seems to have not enough!
Its almost as if all the heat is going out of the chimney instead of heating the water. We have a ceramic lined flue in a fireboard chimney breast, (no brick chimneys here, original council setup) but it worked fine with the old burner. Flue seems to be drawing fine, although the fire doesn't seem to burn excessively even when everything is open, (the last burner was turned down most of the time because it went bonkers if we left the vents open) it takes a lot more coaxing to really get it going for some reason.

I'm panicking now in case the burner is installed incorrectly, or there is a vital something the parkray needs that the Trianco did not...

We are using twice the coal we used before and getting nowhere fast... tried phoning local plumbers etc but can't find one who knows anything much about solid fuel heating! Our engineer friend is stumped too!

Someone please help!
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feel the flow circulator pipe on your should be a 28mm pipe entering at the side of cyl. if hot and the one below is cold then coil airlocked.
Hi, thankyou very much for the reply!

ok, pipe from top of cylinder is hot ish, there are 2 pipes from front, one is hot ish, the other (lower one) is only slightly warm, (That one has an old and no longer connected thermostat on it, not linked to pump switch any more hence the manual on and off) am I right in thinking if that is the one that the thermostat used to use it should be as hot as the others?

Last pipe comes out of floor in front of cylinder and seems to go round the back, that one is very cold, but i'm assuming thats the cold feed one.

Does this help?

...and if we do have an airlocked coil, how do we fix it? (husband very practical, good job one of us is hehe.)
Check the baffle is correctly seated as well if not it can let too much heat escape up the flue.
Other thing as well is you shouldn't really burn coal as it can't cope with the air damper regulating,it tends to slow down the burning too end up with reduced heat output
You should burn coke.
It does sound like an airlock though,check your primaries are rising first.

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erm. i think its red flame, possibly anthracite? is that coke or coal? Lol sorry i just shove it in the bucket.... will light the fire later and add any extra info we can gather to here then. Will check out the theory of airlocked coil, thanks for messages :)
Not necessarily the cylinder coil, it could be the pipes themselves.Check they are rising all the way.It has been known for pipes that are level or sloping the wrong way ever so slightly to workwhen eventually vented of air.
Who can say the problem wasn't there when the original boiler was fitted and eventually started working till you drained the system to fit your new boiler?
Also check if your qualified installer connected the flow and return pipes at opposite sides of the boiler.Anthracite is coke so the fuel is O.K.
You might have to take up floorboards to see the pipes because one might of drooped if they're not supprted properly.
I've seen them not working one minute and then after an air bubble no bigger than you could fit in a shot glass has bubbled out away they go.
ok, hubby says, burner has 4 pipes out of it, top left (as ur facing burner) is flow to radiators, bottom left return from radiators (goes round back of burner, has pump on it), top right gravity feed flow, bottom right gravity feed return.
Is that correct? (by the way, what would happen if those were wrong, surely it wouldnt heat radiators at all?)

some extra info, if my research is correct we have an old gravity system, indirect and possibly open vented judging by the pictures i've found, although we dont have any kind of bleed valve thing on the cylinder. There may be a cold pipe draining point but if there is its round the back (handy).
We do have a vent pipe which leads up to header tank in loft, it comes off the lower of the two side cylinder connections. The Higher one has the not-worked-for-years thermostat on it.

Hmmmm. It was the thermostat (upper) one that was cooler when we had the fire lit, I may have made a mistake in my original post. Damn. I'll double check that tonight when we light it.

Any help to you? Thanks for the info :)
will check the pipe slopes, but we've been using the other burner ten years with no problems, and only messed with the bottom 6 inches of the pipes where they join the burner so its unlikely to be that. Pipework was same, just had to extend a bit here and there so the pipes reahed the holes in the new burner which were slightly offset from the old ones.
Flows and returns should always be opposite corners to ensure even water distribution.
And at the cylinder the pipes at the side going into the coil should be flow at the top(with the expansion/vent pipe) and the bottom is the return(with the cold feed pipe tee'd into it).

The thermostat should Ideally be placed on the return about a foot or so away from the boiler so that when the heat has travelled up the pipe and warmed the cylinder the returning heat automatically starts the central heating pump to prevent excessive hot water or worse still boiling over of the tank.

Sounds like somebody got the pipes mixed up when connecting it up?
Is that crossflowing? I think i read about that. Pipes may not be cross flowed but they are exactly as they were for the old burner, and that was not a problem for last ten years? Isn't crossflowing optional?

Thermastat is quite probably on the wrong pipe, this house was definately built by idiots and wired and plumbed by... well, ex council... that'll be the cheapest bidder then lol.

Thanks for that, a mate has offered to come and replace the thermostat (which is buggered anyway) and put it where it should be. So thats one thing which will get sorted. Yay.

Ok, update: we just discovered the parkray has a wierd metal sliding bit under the top cover (have to take the whole top off to see it), seems to move a section of the throatplate to direct the draught toward the back where the water is.... no mention of it in the manual or in the diagrams, or in the usage instructions.... !!! We're currently testing it in different positions to alter the pull and see wether its simply that the fire is not pulling over the back boiler intensly enough... Not convinced though.

Watch this space!

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