Villager boiler stove

janner

Hello I have a villager wood stove just running radiators but have problems with condensation in wood stove and not all radiators getting hot .could I fit a anti-condensation valve ? If so where best to fit it and do I need second pump etc I have attached a diagram of the system hope this helps it an open vented system

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Grallert

The first thing that comes to mind regarding condensation is cold return water for too long. In other words The wood is burning in a too cool environment. How is the pump controlled?

Which radiator is not heating? and will it ever heat at all?

hot_rod

is the stove big enough for the radiation attached to it ?

janner

IT a downstairs radiator it does sometimes the fire is big enough I just need to stop the cold return water coming in the pump is a grundfos

janner

If I put the f&e tank and vent on flow line and put pump after it would that help circulation

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And how could I plumb in one of these on the system ?

Jamie Hall

Indeed you o need to stop the cold return water from getting to the stove — as much — and you certainly need to keep the wood stove hot enough!

Tackle that one first: the stack or chimney temperature really must be kept above 200 F. The temperature of the stove top — or the stack just above the stove shouldn't be allowed to go below 400 or so except for a short time starting or while the fire is being allowed to die. Otherwise, you will be building creosote in the chimney, and sooner or later you will have a chimney fire — which is not something you want.

As you have discovered, returning cold water or even cool water from a radiator or the like will drop that temperature and give you very real problems.

So… I can see two approaches which might work for you. The simplest, if you have a globe valve or other decent throttling valve on the pumped system, is to reduce the flow to the radiator with that valve to the point where the return water is still nice and warm — warm enough to avoid cooling the stove. This will work best if you consistently fire the stove to the same heat output — but you can also do this with a thermometer on the stove top, and reduce the flow by hand when it seems to be cooling too much.

The other approach is similar: a thermostat on either the stack or the stove top which turns the pump off if the temperature is too low.

Whatever way you choose to go, though, don't run that stove too cool!

janner

HI I do have a stove thermometer and keep fire in safe zone but return tempature always quite cold rads upstairs get hot only one downstairs that don't the f&e tank is on the end of flow line and expansion on end of return line can I rearrange pipping to get better flow ? And fit anti condensation valve?

hot_rod

Yes a return temperature valve would be a wise idea. Use the manufacturers recommendation for proper piping.

Could you have an air lock upstairs?

Here is an explanation and another option.

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janner

Thank you for that would having the feed and expansion on the end of the flow and return runs cause negative pressure causing pump not to push past it ?

Also I have been trying to work out how to pump away from flow tank if I put pump on end of flow just past the header tank would that b better ? And if done that would I need another pump for anti condensation valve by boler

Jamie Hall

Couple of general points here.

First, water is lazy. It will flow in the direction of the least resistance. Therefore, if you want it to flow to a particular radiator, you need to arrange the resistance to other possible flow paths so that it goes where you want it to go. Balancing valves.

Second, you want the expansion tank as near the inlet to the main circulating pump as possible. All the expansion tank does — or can do — is stabilise the pressure at its location, so if it is located close to the inlet of the pump that will guarantee that the lowest pressure anywhere in the system is the pressure of the expansion tank — which is what you want.

Now a mixing valve (such as shown in your picture) is not a satisfactory anticondensation valve in a simple system. Assuming a more or less constant source temperature (your stove), the only way you can bring the return temperature up to a reasonable level is to reduce the flow rate through the radiation (note that this is very different from primary/secondary piping, often used in hot water heating systems, in which the flow rate through the boiler is pumped separately from the flow through the rest of the system).

What is needed is a valve — preferably on the return to the stove — which you can regulate to reduce the flow enough to keep the temperature up in the safe range. Or, as I suggested earlier, simply have a thermostat which will turn the pump off if the return temperature gets too low. It occurs to me that you could also use a modern pump with a delta T control to accomplish much the same thing.

janner

Any chance you could do me a diagram please at the moment my f&e tank is at the end of the line in another building I cannot get a feed near the pump behind boiler so should I move the pump to the end of the line in my first drawing is the location of the f&e tank in relation to boiler and pump ? And feed is on the return line and expansion pipe on flow .thanks

hot_rod

Where are you located? A 15-50 with union connections would be rare in the US?

What you need is a complete system design. We need to know the output of the heat source, what type of radiators, how many, size of the piping, total length of the piping, how many ells, etc.

Without any of the info, best we can do is guess at a system for you.

It could be this simple. This with an over-heat loop also.

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janner

Thank you I'm located in france I can only have gravity feed hot water so with the condensation valve the pump would go on return ? I can only have the feed on opposite end as the system is already fitted through ceilings n under floor so can do a few mods but not replace original flow and returns should I put feed and expansion pipe on flow or return so can get it pumped away from sonp ?

janner

That system would be perfect the only thing is feed water from gravity tank as can't get it down by pump it opposite end of building any ideas ? Would it be best to get a pipe from tank to come down by the pump for the feed ? And what about expansion pipe would that need to come down to boiler to or could that stay at other end ?

Thank you for your help

Jamie Hall

I think we need to know a LOT more about this system. There is a gravity tank? Where? Open to the atmosphere? How is this whole thing piped? I think we have a lot of missing data here — and thus I'd say that any advice up to now — except to adhere to those minimum temperatures — is quite irrelevant.

janner

GRavity tank is just after last radiator on flow and vent pipe next to it on return line all after last radiator I'm in France system was already installed will try and do better diagram thanks

janner

Here is some pics of gravity tank the fill is on end of the line just a blanked of flow pipe after bathroom radiator

U can see end of pipe that is the return line the feed tees into it

That the expansion pipe teed into flow after last rad it also is blanked off

GGravity tank in barn roof feeding return line

janner

Here is a drawing of radiator position and f&e tank etc as it is now

Jamie Hall

And it is that last radiator, near the tank, which doesn't heat well?

What is the relative elevation of the radiators and the water level in the tank? The water level in the tank must be higher than the top of the highest radiator.

Then the other very real possibility is that that radiator has trapped air in it — and water, being terminally lazy as I mentioned, won't bother to flow there.

If there are control valves on the radiators, you can probably get better balance overall by just closing a few (not all the way, just enough.

Otherwise — nothing inherently wrong with the system that I can see off hand.

janner

Thank you so the feed supply from tank is OK coming in after last radiator and the expansion pipe OK on flow line it is blanked after